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The
No. 19
WIMSHURST MACHINE
HOW TO MAKE AND USE IT
A Practical Handbook on the Construction and Working of the
Wimshurst Machine and other Static Electrical Apparatus
FULLY ILLUSTRATED
I
N

Dubelle's Famous Formulas ,
KNOWN AS
Non Plus Ultra Soda Fountain Requisites of Modern Times
By G. H. DUBELLE .
A practicalReceiptBookfor Druggists
, Chemisis, Confectioners and Venders
of Soda Water.
SINOPSIS OF CONTENTS.
INTRODUCTION. Ivotes on natural fruit juices and improved me
thods for their preparation Selecting the fruit. Washing and
pressing the fruit. Treating the juice . Natural fruit syrups and
mode of preparation . Simple or stock syrups.
FORMULAS.
FRUIT SYRUPS. --Blackberry, black current, black raspberry, ca.
tawba, cherry, concord grape, cranberry, lime, peach , pineapple,
plum ,quince , raspberry, red current,red orange
, scuppernong grape,
strawberry, wild grape. New IMPROVED ARTIFICIAL FRUIT SYRUPS
Apple, apricot, banana, bitter orange, blackberry, black current,
cherry, citron, curacoa, grape, groseille, lemon, lime
, mandarin , mul
berry, nectarine, peach , pear, pineapple, plum, quince, raspberry,
red current, strawberry, sweet orange, targerine, vanilla. FANCY
SodA FOUNTAIN SYRUPS. - Ambrosia, capillaire
, coca -kina, coca van
illa, coca-vino, excelsior, imperial, kola coca , kola-kina, kola -vanilla,
kola-vino, nectar, noyean, orgeat, sherbe', syrup of roses, syrup of
violets. ARTIFICIAL Fruit EssENCES.- Apple, apricot
, banana, berg
amot. blackberry, black cherry, black currant, blueberry, citron,
cranberry, gooseberry, grape lemon, lime fruit, melon, nectarine
,
orange, peach , pear, pineapple, plum ,
quince, raspberry, red currant;
strawberry. CONCENTRATED FRUIT PHOSPHATES, Acid solution of
phosphate, strawberry, tangerine, wild chc ry. - 29 different formula s.
New MALT PHOSPHATES - 36. FOREIGN AND DOMESTIC WINE PHOS
PHATES - 9. CREAM- FRUIT LACTARTS -28. SOLUBLE FLAVORING EX
TRACTS AND ESSENCES-14. NEW MODERN PUNCHES -18. MILK
PUNCHES -- 17. Fruit PUNCHES - 32. FRUIT MEADS - 18. NEW FRUIT
CHAMPAGNES - 17
. New EGG PHOSPHATES — 14. FRUIT JUICE SHAKIS
-24 EGG PHOSPHATE SHAKES. Hot EGG PHOSPHATE SHAKES.
WINE BITTER SHAKES - 12. SOLUBLE WINE BITTERS EXTRACTS - 12
New ITALIAN LEMONADES—18. ICE CREAM SODAS - 39. Non -Poisoi
ous Colors. FOAM PREPARATIONS. MISCELLANEOUS FORMULAS-20.
LATEST NOVELTIES IN SODA FOUNTAIN MIXTURES-7. TONICS. - Bee
iron and cinchona; hypophosphite ; beef and coca ; beef, wine and
iron ; beef, wine, iron and cinchona '
; coca and calisaya. LACTART
- Imperial tea ; mocha coffee ; nectar: Persian sherbert. PUNCHE 5.
EXTRACTS.- Columbia root beer; ginger tonic ; soluble hop al
LEMONADES.-- French ; Vienna. Egg nogg. Hop ale. Hot tom . Ma.
wine. Sherry cobbler. Saratoga milk shake. Pancretin and wine.
Kola -coco cordial. Tron malt phosphate. Pepsin , wine and iron, etc
157 Pages, Nearly 500 Formulas. 12mo, Cloth. Price $1.65 postpaid

THE
“ WIMSHURST
” MACHINE
HOW TO MAKE AND USE IT
A Practical Handbook on the Construction and Working
of the Wimshurst Machine, including Radiography
and Wireless Telegraphy, etc., and other
Static Electrical Apparatus
BY
ALFRED W. MARSHALL , Asso . M. INST. E. E.
SECOND EDITION , REVISED AND ENLARGED
NEW YORK
SPON & CHAMBERLAIN , 120 LIBERTY St.

Copyright, 1908
BY SPON & CHAMBERLAIN
CAMELOT PRESS, 226-228 WILLIAM ST., NEW YORK, U. S. A.

537.23
M 35 W
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PREF CE.
The average amateur probably regards static
electricity with distrust, as an elusive thing-dry
to read about, and the experiments which he tries
never giving any perceptible result. He has pos
sibly made or acquired some antiquated frictional
machine which can never be coaxed to work, and
having exhausted his patience upon it in vain, re
verts to primary batteries, or gives up electricity
altogether as beyond his capabilities. As a mat
ter of fact, static electricity is a fascinating sub
ject when studied experimentally; and if the ama
teur can be sure of obtaining big sparks, and get
a few not too big shocks , at the very start, he will
be happy, and soon find himself led on to continue
his experiments, obtaining a great deal of instruc
tion and amusement.
Fortunately , there exists a static machine which
can be relied upon to work under almost any con
ditions. It is the Wimshurst Influence Machine ,
the invention of a British engineer, the late Mr.
James Wimshurst. The object of this book is pri
marily to explain the machine in a simple and
practical manner so that an amateur can know
how to make it work. Some easy experiments are
46723
3

4 PREFACE
given , and a few hints and examples which will
guide him if he desires to make one of these ma
chines . Other chapters explain briefly the use of
some of the well -known appliances used for static
experiments , as this information will assist the
reader to understand the action of the Wimshurst
machine as well as enlarge his knowledge of the
subject in general.
A. W. M.

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CONTENTS .
CHAP. PAGE
1 . THE WIMSHURST MACHINE- INTRODUCTORY 7
2. Static ElectriCITY 12
3 . The ELECTROPHORUS 15
4. THE ELECTROSCOPE 19
5. CONDENSERS 23
6. The LEYDEN JAR . . 30
7. THE PARTS OF A WIMSHURST MACHINE AND THEIR
Use 35
8. MAKING AND MANAGEMENT OF WIMSHURST MA
CHINES 43
9. Some EXAMPLES OF WIMSHURST MACHINES 59
10. A LARGE WIMSHURST MACHINE 68
11 . A WIMSHURST MACHINE FOR X-RAY WORK . 94
12 . EXPERIMENTS FOR WIMSHURST MACHINES 103
.
5

pasiooring Iibrary
CHAPTER I.
INTRODUCTORY .
The Wimshurst Influence Machine is a particular
pattern for generating static electricity by induc
tive action between charged metal plates instead
of a rubbing action , as in a frictional machine .
It is called after the name of the inventor, James
Wimshurst.
In its simple form the machine consists of a pair
of glass discs mounted upon a spindle, so that they
can be rotated in opposite directions at a com
paratively high rate of speed. These discs are
placed so that their inner surfaces are as close to
gether as practicable to allow of rotation . Upon
the outer surfaces are cemented a number of sector
shaped strips of thin brass or tinfoil, spaced at
equal distances. Each disc has the same number
of these sectors , so that at a given instant the sec
tors on one disc will be exactly opposite to those
on the other.
Facing the outside surface of each plate is a
metal rod, to the ends of which are fixed some light
tinsel brushes, so adjusted that they touch the
metal sectors as the latter pass the brushes during,
the rotation of the plates . These neutralizing rods,
as they are called, make metallic connection be
ñ
1

8 THE WIMSHURST MACHINE
tween diametrically opposite sectors upon respec
tive plates , and are set at a right angle to each
other, or less , to 60 degrees.
Inductive Action . When the plates are rotated
an inductive action takes place between the sec
tors of one plate and the sectors of the other.
The charge of static electricity existing upon any
sector of one plate exerts an influence upon the
adjoining sector of the other plate, according to
the rules of static electricity (see Static Electricity,
also Electrophorus ).
If a pair of diametrically opposite sectors of one
plate are respectively positively and negatively
charged, they will act inductively upon the ad
joining similar pair of sectors of the other plate .
The neutralizing rod, whose brushes press upon
this second plate, makes metallic connection be
tween the sectors which are being acted upon , and
allows the induced electric charges to distribute
themselves. As the plates continue to rotate , the
distributed charges are carried on the sectors to
the collecting combs , where they are distributed
to the discharging rods. At any instant there are
thus four pairs of sectors engaged inductively,
two pairs being covered by each neutralizing rod.
As the plates continue to rotate, a cumulative
action takes place , the sectors of each plate acting
alternately as inductors, the charges thus increas
ing in strength until leakage dissipates the accu
mulation or the charge is conducted away by the

INTRODUCTORY 9
collecting combs . If the collecting combs are re
moved the charges will still be produced, but then
merely leak away across the plates, which will
glow with a luminous discharge. The reason that
the machine will excite at starting is probably due
to an uneven electrostatic condition permanently
existing , by which some of the sectors are in a dif
ferent state of charge to the others; but the action
of these machines is not at present entirely under
stood.
Collecting Points. Unless the collecting points
are exactly alike and at the same distance from
the plates , the action of the machine is affected and
electricity may be only collected from one disc,
the other not contributing to the collected charges
for the time being. Positive electricity is collected
at one comb and negative at the other ; these signs
remain constant, the polarity not reversing during
the rotation of the plates . If, however, a fixed
glass plate is placed between the rotating plates ,
the polarity reverses at regular intervals ; this is
called an alternating Wimshurst machine.
To increase the output, two, three , or more pairs
of plates may be combined in one machine, each
successive pair being a repetition of the construc
tion of the first pair , all being carried upon the
same supporting spindle and contributing to one
pair of discharging rods.
Leyden Jars. If Leyden jars are connected to
the collecting combs , the inner coatings to the

combs and the outer coatings to earth , these jars
will become charged , the result being that a
thicker spark at less frequent intervals will occur
between the discharging balls , according to the
capacity of the jars. Without jars the machine
gives sits maximum length of spark , which is of
thin character and at more frequent intervals.
Uses. Wimshurst machines are used for illumi
nating vacuum tubes to produce X-rays or give
effects of discharge in vacua, taking the place of
an induction spark coil in this respect. They are
also used for electro-medical treatment, and wire
less telèğraphic experiments.
The machine should be arranged to suit the con
ditions of working when required for a particular
purpose. Though comparatively unaffected by
atmospheric conditions, a dry atmosphere is de
sirable.
When used for electro -medical treatment, or
production of X -rays, the wires conducting the
electricity to the tube or apparatus are not con
nected directly to the discharging rods, but to a
pair of discharging balls which are mounted upon
insulated supports. These balls are placed near
to the discharging balls of the machine, and a
spark discharge is allowed to pass over the inter
vening air -space between the respective balls.
Such an arrangement is called a spark gap . The
object is to equalize the rate of discharge and pre
vent the electricity leaking to earth from the ma

INTRODUCTORY 11
chine, as will occur if the conducting wires are con
nected directly to the discharging rods.
Wimshurst machines are also called influence
machines, a term which includes others, such as
the Voss and Holtz, etc.; all these act by electro
static induction , differing in this respect from ma
chines in which electricity is produced by a rub
bing action .

CHAPTER II.
STATIC ELECTRICITY.
Electricity is supposed to exist upon all bodies,
and in a neutral condition unless disturbed. By
certain processes, such as rubbing two dissimilar
substances together, the neutral condition of the
electricity is upset. When the substances are sep
arated an excess of electricity remains upon one of
them , and a deficit of electricity upon the other,
as compared to their normal condition. Each sub
stance is then said to be charged with electricity.
As this electricity is in a state of rest as com
pared to the flow of electricity from a battery or
dynamo, it is called static electricity. Each sub
stance is said to have a static charge of electricity
residing upon it.
The substance which has the excess of electricity
is said to be positively charged and that which has
a deficit of electricity is said to be negatively
charged. The charges are called positive and nega
tive electricity respectively. The typical exam
ples are a glass rod rubbed with a piece of silk, the
glass becomes positively charged and the silk nega
tively charged ; a stick of sealing-wax rubbed with
cat's skin or flannel, the sealing-wax becomes
negatively charged and the cat's skin or flannel
12

STATIC ELECTRICITY 13
.
positively charged. If the respective positive and
negative charges are imparted each to a metal
body, and these are brought into contact, the
charges combine , and the electricity is restored to
the neutral condition . The sign + is used to
indicate a positive charge and the sign — to indi
cate a negative charge. Bodies charged with +
electricity repel one another but attract bodies
charged with — electricity. Bodies charged with
electricity repel one another but attract bodies
charged with + electricity.
The subject of static electricity embraces a range
of phenomena including atmospheric electrical
effects,
Some of the instruments in everyday use for
measuring electric pressure depend upon static
electrical effects for their working; as examples,
the Kelvin electrostatic voltmeters and quadrant
electrometers . For medical treatment static elec
tricity is used. In electrical engineering practice,
where machines and wires generating and trans
mitting dynamic electricity at very high voltage
are employed, static electrical effects are produced
and have to be consideerd.
Static electricity is produced in quantity by
frictional electrical machines and influence ma
chines ( such as the Wimshurst Machine). The
Leyden jar, electrophorus , condenser and proof
planes are apparatus used for investigating the
properties of and experiments with static elec

tricity. Lord Armstrong produced static elec
tricity by means of a jet of steam from a boiler.
It was made to strike against some insulated metal
lic points, which collected a positive charge; this
apparatus is known as the hydroelectric machine.
A charge of static electricity resides upon the
outside of a conductor ; a hollow ball or rod, or
wood ball or rod, covered with tinfoil is as effec
tive in this respect as if made of solid metal.

CHAPTER III
THE ELECTROPHORUS
An apparatus for generating static electricity.
It consists of a thick disc , usually called the cake,
of some insulating substance (A , fig 1 ) -ebonite
or a compound of resin --which is placed in a metal
tray, B. A thin metal disc, C, usually called the
cover, of approximately the same size as A , and
fitted with an insulating handle, D , completes the
instrument.
A charge of electricity is produecd in the follow
ing way :—The disc, A, is rubbed, or repeatedly
struck with a piece of silk or cat's skin ; this will
cause the disc to become charged with negative
electricity . The disc, C , is then placed upon A ,
which acts inductively upon it, causing it to assume
a positive state of electric charge. This state ,
however, only exists whilst C is upon A ; if C is
lifted by means of the insulating handle, D , it
will assume a zero condition of electric charge as
soon as it is away from the influence of the charge
which is on A. If , however, whilst C is resting
upon A it is touched by the finger of the operator
(which is equivalent to connecting it to earth) ,
the charge upon A will repel negative electricity
15

from C to earth and attract a further amount of
positive electricity to C. When , therefore, the
finger is removed, this positive charge is imprisoned
on C, and may be carried away if C is lifted by
means of D. This charge can be stored up in a
Leyden jar by touching the
knob of the jar with C ; or
if, whilst holding C by D ,
the operator presents one
D of his fingers to the disc
C , a spark will pass and
the charge be neutralized
by a rush of negative elec
tricity.
The charge which was
originally imported to A
dissipates only at a slow
rate ; it is therefore possi
ble to obtain a number
of successive positive
charges on C by repeating
the operation described,
all of them being produced
by the inductive action
of the one original charge
FIG. 1 . on A. If such a succession
of charges be imparted to
the inner coating of a Leyden jar, it may be
highly charged by this means . When the charge
on A becomes weak, a few blows with the silk
or cat's skin will restore it to its former strength.
A
B

THE ELECTROPHORUS 17
It is important that the electrophorus should be
free from moisture and used in a dry atmosphere.
The full theory is somewhat more complicated, and
involves the principle of the electric condenser, but
the explanation given sufficiently describes its
action to enable a beginner to form some idea of
the way in which the apparatus is used and the
electrical effects take place.
The tray, B , is an important part of the apparatus
and assists in the action of the charge on A upon C.
To produce a negative charge of electricity upon C
it is necessary that A is composed of some material
such as glass, which can be excited with a positive
charge of electricity.
The apparatus may, however, be used in an in
verse manner-that is, if C is placed upon a table
and A. is turned upside down, the result of the
inductive operation is to produce a negative
charge of electricity upon B , which charge can be
stored in a Leyden jar or imparted to any con
ductor of electricity. It is, of course , necessary
that B fits tightly upon A , so that the two may be
lifted by D , which is for this purpose unscrewed
from C and screwed into B , as indicated in fig . 1
by the dotted lines.
The operation is as follows :-Excite A by
rubbing or striking it with the cat's skin . Whilst
holding it some distance from C by means of the

handle touch B to make contact to earth . Now
rest A upon C. When the cake A is upon C the
tray B is to be touched by the finger of the opera
tor ; upon lifting A and B together away from C,
by means of D , it will be found that B is negatively
charged with electricity.

CHAPTER IV
THE ELECTROSCOPE
This is an instrument used for indicating whether
a substance is charged with electricity or not, and
whether the charge is positive or negative.
Gold - leaf Electroscope. There are several kinds
of electroscopes , but the pattern generally used
is called, from its construction , the gold - leaf elec
troscope . The principal part of the instrument
consists of a pair of strips of gold leaf L , L, Fig. 2 ,
suspended by their upper ends from a vertical
metal rod , R. A glass shade, S, surrounds the
goid leaves and acts as a support for R , which is
fixed in a plug of ebonite or other insulating
material, E , fitting in the neck of S. A base, B ,
frequently of metal, completes the apparatus.
The interior of the shade should be in a dry con
dition if the electroscope is to be used with success.
When uninfluenced by a charge of electricity the
gold leaves , L , L, will hang vertical , so that they are
close together. If the knob, K , be touched by a
body which is charged with electricity the gold
leaves, L, L, will diverge and stand at an angle
as shown in the illustration ; if there is no change
of electricity upon the body the leaves , L, L , will
not move .
19

It is not always necessary for the charged body to
touch K ; if it is held near to K the leaves , L, L ,
will usually be affected . The reason the leaves , L, L ,
diverge is that as each becomes charged with elec
tricity of the same sign - that is, positive or nega
KO
R
S
B
Fig. 2
tive—the two charges repel each other, conse
quently the leaves move outwards at their lower
ends .
Positive or Negative charge. To ascertain
whether the charge on a body is positive or nega

THE ELECTROSCOPE
21
tive it is necessary to impart a charge of known
sign to the leaves, L, L , as follows:
-A body which
has been electrified positively - for instance, such
as a glass rod which has been rubbed with silk
is brought near to the knob , K. The leaves, L , L,
diverge, because positive electricity is repelled
from K to the ends of the leaves , as the glass rod
will act inductively upon the electroscope. It will
attract negative electricity to K. If the operator
now touches K with a finger of his other hand the
positive electricity will then flow away from the
leaves to earth, and they will fall together. The
negative electricity will be retained at K by the
action of the glass rod , which is still, of course ,
held near to K. The operator now removes his
finger from K , and thus imprisons a charge of
negative electricity upon it , held by the influence
of the glass rod. The glass rod is finally taken
away to a considerable distance from K , and the
leaves, L , L , will diverge, because the imprisoned
charge distributes itself over K, R , and L, L , thus
becoming charged with negative electricity. The
instrument is now ready to be used for ascertaining
the sign of an electric charge.
Charged Body. If the charged body is brought
near to K, and the charge is of negative sign , the
leaves, L , L , will diverge more widely apart, because
the inductive effect of a negatively charged body
will be to repel more negative electricity into the
leaves from K, and , therefore, they will repel each

other with greater force . If, however, the body is
charged with electricity of positive sign the leaves,
L, L, will collapse and approach one another,
because the inductive effect of a positively charged
body will be to attract the negative electricity with
which the leaves, L , L , are charged up to K ; they
will, therefore, either not be repelled at all or the
effect of repulsion will be much weaker and they
will approach one another. It does not matter
whether the test charge given to the leaves be posi
tive or negative.
charge them with positive electricity a stick
of sealing-wax which had been rubbed with a
cat's skin could be used . The sealing-wax would
be negatively charged , and therefore induce and
imprison positive electricity upon the gold leaves.

CHAPTER V
CONDENSERS
An electric condenser consists of a pair of con
ducting surfaces, which may be metallic plates or
wires, tubes, or anything in the nature of a metallic
surface , the two surfaces being kept at a distance
from one another by an insulating substance.
One of the well-known forms of condensers is
the Leyden jar (see Leyden Jar) .
Another much-used form consists of two sets of
tinfoil sheets, interleaved with each other, the two
sets of leaves being separated by sheets of paper
or mica interposed between each pair of tinfoil
sheets (see Fig. 3) , which represents the arrange
ment of a condenser.
Looking at the edges of the sheets, T 1 and 1 2
are the interleaved tinfoil sheets , there being
four sheets of T 1 and four sheets of T 2 , the sheets
of each set being all joined together; P , P , are the
sheets of paper which separate the two sets of
tinfoil sheets from one another. The sheets of
paper are larger in area than the tinfoil sheets
(see small sketch) , so that when the edges are
pressed together, the tinfoil sheets are each sur
rounded by paper except where the connections to
the terminals are made .
23

The use of a condenser is to hold or absorb a
charge of electric energy, and either retain it for
a comparatively great length of time or immedi
ately restore it again to the cricuit from which
it was obtained .
Connected to a Battery. If a condenser is con
nected to a battery (see Fig. 4) , electricity will
flow from the + pole of the battery to the set of
P
-P
TERMINAL
-P
-P TERMINAL
-To
To
Ta
구
-T₂
T
Ta
-P
P.
-P
TINFOIL
PAPER
FIG. 3
tinfoil sheets which form one side of the condenser ;
these sheets will absorb a positive charge of elec
tricity, the quantity depending upon the length of
time during which the battery is connected , and
upon the capacity of the condenser, as it is called .
The tinfoil sheets which are connected to the.
pole of the battery will become deficient in elec
tricity ; they will receive a negative charge , as it is
termed — that is, electricity may be imagined to

CONDENSERS 25
have gone out of that side of the condenser, passed
through the battery, and accumulated at the +
side .
If the battery remains connected during a suffi
cient length of time , the condenser will become
fully charged , and if the battery is disconnected ,
the condenser will retain its charge for a certain
length of time. If, now, a piece of wire is joined
CONDENSER
BATTERY
Hun
FIG. 4
to the terminals of the condenser, it will give back
the charge which was accumulated at the + side
the current flowing along the wire and returning
to the -- side of the condenser (see Fig. 5) , until
equilibrium has been restored .
Positive charge. As the positive charge is
equal to the amount of deficit represented as the
negative charge , no storage of electricity has really

occurred. A condenser in fact stores electric
energy but not electricity. The capacity of a
condenser to absorb a charge of electricity depends
upon three things — first, the area of the metallic
plates ; secondly, upon the distance between them ;
thirdly, upon the kind of substance used to keep
them apart, or dielectric as it is called. The
larger the area of the plates , and the less the
distance separating them , the greater will be the
+
CONDENSER
WIRE
Fig. 5
quantity of the charge of electricity which the
condenser can absorb.
Insulation . As regards the effect of the sub
stance used to separate the plates, this will depend
upon what is called its specific inductive capacity,
which means the effect which it will have in com
parison with that which would be produced if the
metallic plates were separated by air. This effect

CONDENSERS 27
is greater or less according to the material em
ployed . Paraffin , wax , and shellac are much used ,
these materials having fairly high values and being
easy to manipulate. It is necessary, however,
to use a dielectric which has sufficient mechanical
strength to prevent a spark discharge taking place
between the metallic surfaces and piercing the
dielectric ; this would short-circuit the condenser,
and it would not retain a charge of electricity.
Paper, glass, or mica are therefore often used in
conjunction with paraffin , wax, or shellac.
+
TERMINAL TERMINAL
FIG. 6
The capacity of a condenser is measured in farads.
The farad (derived from Faraday) is the unit in
which measurement of the capacity of a condenser
is expressed; it is equal to the capacity of a con
denser which , when charged with a current having
a strength of one ampere for one second of time,
will have a pressure of one volt existing between
its terminals. Such a condenser would be of so
great a size that it could not be used in practice ;
it is therefore the custom tr express condenser

measurements in microfarads— that is, in units
of one-millionth of a farad .
Condensers are used for the purpose of absorbing
sudden fluctuations of current , as in the use of a
condenser in connection with the primary coil of an
TERMINAL TERMINAL
Fig. 7
induction coil, or for accumulating a number of
small charges until they become one large charge,
as when condensers in the form of Leyden jars are
used in connection with a Wimshurst or other
influence machine . Condensers are also used in
telegraphy, and occasionally to assist in producing

CONDENSERS 29
a difference of phase in the starting coils of single
phase alternating current electric motors. The
effect of a condenser is the opposite to that of
self-induction in a circuit.
Self - induction retards the rise of flow of an
electric current, and retards the diminution of
flow ; a condenser assists the rise of flow of an
electric current by absorbing the current until it
is fully charged, and retards the diminution of
flow of current by giving back its charge of current
to the circuit when the flow of current tends to
diminish ; self - induction , therefore , is neutralized
to a greater or less extent by the presence of a
condenser. Condensers may be connected in
parallel with each other, or in series with each other.
The latter method is called connecting them in
cascade (see Fig. 6) .
When connected together in parallel (see Fig. 7 )
they practically become one large condenser,
having a pair of plates of the area of the com
bined + and - surfaces respectively. When
connected in cascade , each condenser acts upon the
next one in series with a cumulative effect.

CHAPTER VI
THE LEYDEN JAR
(See also CONDENSER)
The Leyden jar is a well- known and recognized
form of electrical condenser. As usually made,
it consists of a glass jar (Fig. 8) , coated inside and
outside with tinfoil to a distance of about three
quarters of the height of the jar, and over the
bottom as well. A lid , made of wood or other
insulating material, is fitted to the mouth of the
jar, and supports a metal rod, which is fitted with
a metal knob at its upper end and is electrically
connected to the tinfoil on the inside of the jar.
A common method of making this connection is
by means of a metal chain , which is attached to
the lower end of the rod and rests upon the tin
foil. A mass of lead shot , acid, or a quantity of
gold-leaf is sometimes used in place of the tinfoil
coating inside the jar. The effect produced is the
same in each instance .
A Leyden jar is employed for the purpose of
holding a charge of static electricity ; it is then
said to be in a charged condition.
The charge can be obtained from a frictional or
Wimshurst machine or from an induction coil.
30

THE LEYDEN JAR 31
The usual way to charge a Leyden jar is to place
the knob within sparking distance of the dis
charging knob of the machine, the jar being held
in the hand of the operator by means of the outer
SPARK DISCHARGE
Nina
WIRE
INNER
COATING
OUTER
COATING
FIG. 8
coating, which is thus connected to earth . The
charge of static electricity passing from the ma
chine to the inner coating of the jar attracts an
electric charge of opposite sign from earth to the

outer coating and holds it there, the two charges
mutually attracting each other and endeavoring
to combine. The jar is then in a charged condition .
If a metallic connection is now made from the
outer coating to the knob , the two charges will
combine , a spark taking place as the connecting
metal approaches the knob . The jar is then in a
discharged condition. This discharge takes place
in a violent manner ; the operator will receive a
shock if the discharge takes place through his body.
For instance, if whilst holding the jar by the
outer coating with one hand the other hand is
presented to the knob, the shock will take place
through the body of the operator. To prevent
this the discharge can be effected by means of a
piece of insulated wire bent to a semicircle ; it is
necessary , however, to make contact with the
outer coating first, so that the wire is in contact
with it before it touches the knob. The charge is
then diverted through the wire. If the jar is
placed upon an insulating plate or stand, however,
the knob may be touched with impunity.
It can be shown that the charge resides upon
the surface of the glass jar and not upon the metal
coatings by means of a specially constructed jar,
having removable coatings in the form of metallic
cups ; the jar being charged is placed upon an in
sulating plate, the inside coating is lifted out , and
then the glass jar lifted from the outer coating.
These component parts can be handled with im
punity, no signs of electrification being apparent

THE LEYDEN JAR 33
yet when they are reassembled the jar will be in a
charged condition , and may be discharged in the
usual way.
To charge from an induction coil, the knob is
connected to one of the discharging rods of the
coil and the outer coating to one end of the second
ary ( see Fig. 9) . The discharging rods are sepa
ON
Fig. 9
rated so as to allow a stream of sparks to pass ,
the jar becoming charged during the sparking.
Leyden jars are used to accumulate a succession
of small charges , and then discharge them as one
large discharge , as when fitted to a Wimshurst
machine. They are used as a reservoir to main
tain an electrified body in a charged condition,

the body being connected to the knob of the jar
and insulated from earth. They are used generally
for condenser effects. A number of Leyden jars
can be connected together either in series or parallel
to form a battery of jars . When connected in
parallel the outer coatings are all connected me
tallically together or to earth , and all the knobs
are metallically together.
Connected in Series. When connected in series,
or cascade as it is also called, the jars are all in
sulated from the ground; the knob of the first jar
receives the charge, its outer coating is connected
to the knob of the second jar, whose outer coating
is connected to the knob of the third jar, and so
on throughout the series. The outer coating of
the last jar is joined to earth .

CHAPTER VII
THE PARTS OF A WIMSHURST MACHINE
AND THEIR USE
Glass Plates. The principal part of the machine
is the pair of glass plates. Each plate is mounted
upon a boss of wood or ebonite provided with a
central hole , so that it can rotate easily upon the
supporting spindle . This spindle is fixed in the
framework and does not rotate . Each boss is
provided with a groove to take the driving belt
by which the plate is rotated. The electricity
is produced at the surfaces of these plates and not
at any other part of the machine. By means of
the driving belts the plates are made to rotate in
opposite directions. During the rotation charges
of electricity, are accumulated upon the surface of
the plates. If no arrangement is provided to
collect the electricity it will dissipate over the
surface of the plates and away in air by a luminous
discharge .
Neutralizing Rods. The second essential part
of the machine is the pair of neutralizing rods.
They consist of brass (or other metal) , each rod
being provided with a soft metal foil or tinsel
brush at each of its ends. The rods are bent so
35

that these brushes make contact against the outer
surfaces of the glass plates. Electricity is not
generated by the rods or brushes. Their use is
Fig. 10
to connect diametrically opposite parts of the
surface of the plate against which each respective
pair are pressing : they may connect these parts
with earth.

PARTS OF WIMSHURST MACHINE AND THEIR USE 37
Leakage. These two principal parts, viz. the
pair of plates and pair of neutralizing rods, are
thus the generating portion of the machine . If
the rods are set to correct angular position and the
plates rotated in opposite directions to one another,
charges of static electricity accumulate upon the
surfaces of the plates . As the rotation is con
tinued the charges increase until the insulation
or capacity of the plates to hold the electricity is
exceeded . Leakage then occurs and continues,
the electricity being dissipated at the rate at which
it is produced.
Rotating Mechanism . The means employed
to rotate the plates is of secondary importance ,
though at least one maker of these machines holds
the opinion that they should be rotated with equal
velocity. To secure this he uses a positive drive,
consisting of cycle chains and sprocket wheels
(Fig. 10,) which shows the framework of a large
Medical Wimshurst Machine with the Plates re
moved. This same arrangement could be utilized
in the construction of a much smaller machine .
Usually the plates are driven by means of round
leather belts from a shaft placed in the base frame .
A pair of wood V-grooved pulleys are fixed upon
this shaft , one to drive each plate . They are of
equal size , but several times larger than the
diameter of the plate bosses, so that the plates are
speeded up , one revolution of the shaft producing
several revolutions of the plates. One of the

driving belts is crossed , so that the plate to which
it is supplying motion will rotate in the reverse
direction to that in which the shaft rotates. Elec
tricity will not be produced unless the plates rotate
in the proper direction ; this can be found by trial.
The belts and pulleys are merely a means for ro
tating the plates ; they do not generate the elec
tricity.
Collecting the Electricity. To enable the elec
tricity to be utilized, some means of collecting it
from the plates must be provided.
The usual arrangement is two pairs of metal
combs fixed so that two combs are presented with
their teeth pointing towards the outer surface of
each plate . The length of each comb is about one
fourth of the diameter of the plate. They must
be supported by some material of high insulating
' property , or the electricity will escape to earth by
way of the support. Glass of suitable quality is
usually employed for these supports. The back
and front combs at the respective right- and left
hand sides of the machines are in metallic con
nection with each other ; generally the two sets of
teeth on each pair are fixed to one bar of brass,
which is bent to a U , so that it embraces the
edges of the plates : this is only for convenience of
construction. These combs are merely a collecting
device and do not produce electricity.
In some machines a thin blade of metal is used
instead of points. The points are not required

to touch the surface of the paltes. A charge of
static electricity prefers to escape from a point
or towards a point . If a sharp edge or point of
metal is presented towards a charged body, the
electricity will flow to the edge or point ; contact is
not necessary. It would not be practicable (and
it is not desirable ) to have the points or edges in
contact with the rotating plates. Positive elec
tricity collects at one part of the plates and nega
tive electricity at the other. The combs at the
right hand will each collect the same kind of elec
tricity, and it will be the opposite kind to that
produced and collected at the left hand. If the
combs are connected to any suitable apparatus,
the respective charges of positive and negative
electricity will be conducted away from the ma
chine as produced and may be utilized as desired .
Discharging Rods. It'is usual to fit discharging
rods to the combs, the ends of the rods being
capped by metal balls. They need not be curved ,
and may be hinged or jointed in any convenient
manner to permit movement for purposes of ad
justment. They do not serve in any way to pro
duce electricity, but are a means of discharging
it from the collecting combs. The balls retard the
electric charge in leaking away by silent discharge,
which would take place more rapidly if points were
used, as with the discharging rods of an induction
spark coil. One ball is smaller than the other and
should be upon the rod connected to the positive
collecting combs.

There are thus the following parts: the pair of
plates and pair of neutralizing rods forming the
electricity producing portion ; the two pairs of
combs forming the portion by which the electricity
is collected ; the discharging rods forming a spark
gap and means of conveying the electricity from
the collecting combs ; the driving shaft pulleys and
belts, by means of which the plates are rotated .
The supporting framework may be of any con
venient design .
Collecting Combs. If a condenser is connected
to each of the pairs of collecting combs, so that
one coating is in metallic contact with the pair
of combs and the other coating is connected to
earth , the respective positive and negative charges
are retained for a greater length of time. The
condensers , in fact, are charged by the machine .
When the charges reach their limit the condensers
discharge and the process of charging commences
again. Without the condensers the electricity
discharges as thin sparks at comparatively fre
quent intervals of time , if the discharging rods
are set to a suitable width of opening. With the
condensers connected the electricity discharges
as comparatively thick sparks at less frequent in
tervals of time , according to the particular size
and capacity to the condensers. This result is
caused by an accumulation of charges which are
stored up by the condenser and discharged as a
thick, powerful spark, instead of being discharged
as a number of thin , weaker sparks.

Condensers are usually applied to these ma
chines in the form of Leyden jars (see Chapter VI).
and frequently incorporated as a part of the ma
chine , being made to serve as supports to the col
lecting combs. They do not act as producers of
electricity, even when made an integral part of
the machine in this way ; they are accessory, and,
entirely serve the purpose of concentrating the
electricity as it is produced by the rotating plates.
The machines will work perfectly without them ,
Their use is determined by experimental considera
tions.
Increase of Output. Assuming that a certain
quantity of electricity is produced by one pair of
plates of a given size , the output of such a machine
can be increased by adding a second pair of plates.
This should double the output of electricity. The
second pair of plates will require to have its own
pair of neutralizing brushes and arrangement of
collecting combs. To further increase the output
of the machine a third pair of plates and so on can
be added , up to any number of pairs convenient
for practical construction. These are called multi
ple plate machines .
One pair of neutralizing rods will serve to carry
the neutralizing brushes for the entire series of
plates , but each plate must have its pair of brushes.
The collecting combs deliver to the one pair of
discharging rods . All the right-hand side combs
can therefore be carried by one support , and all the
left-hand side combs by the other support.

* 42 THE WIMSHURST MACHINE
A multiple plate machine therefore merely con
sists of a multiplication of the generating portion
of a single machine, and may be regarded as
several single machines connected in parallel, all
the positive and all the negative terminals being
respectively connected together. One pair of
discharging rods will serve to conduct away the
combined charges.
If condensers are used they may be in the form
of one condenser to each positive and negative
collecting comb, or all the respective condensers
combined as one large one of equal capacity. A
multiplication of the driving gear is required, so
that each plate is provided with its own belt and
pulleys. The two plates of each pair must rotate
in opposite directions to one another. Half of
the total number of plates will therefore rotate in
one direction , and half of the total number in the
opposite direction. All the plates are supported
upon the one fixed spindle.
inrich j

CHAPTER VIII
MAKING AND MANAGEMENT OF WIMSHURST
MACHINES
Plates. These may be of glass or ebonite.
Glass was preferred by Mr. James Wimshurst, the
inventor of the machine , and it seems to give best
results ; ebonite , however, will do very well.
Perhaps it would be best for a novice to adopt
glass, if conveniently procurable. Ebonite is
liable to warp and to lose its insulating qualities
by the action of light , but it is adapted for higher
speeds than glass. Window glass is suitable ;
the whiter kind should be selected — that having a
decided green tinge does not appear to be so good
an insulator.
Plates can be obtained from makers of electrical
apparatus. If procured from a glass merchant,
they should be tested before being fitted up . To
do this, warm the plate thoroughly and use it as
the " cake " of an electrophorus (see Chapter III) ,
exciting it with silk. Should you fail to obtain a
good spark of reasonable length from the “ cover,"
say one to two inches or more, the glass should be
regarded as unsuitable. The glass may be warmed
and rubbed with silk, and then tested to ascertain
if a good spark can be obtained when the finger is
43

presented to it. A larger plate should give a spark
of greater length than a smaller one .
Glass plates must be thoroughly coated all over
with shellac varnish . It may be applied with a
brush , and is made by dissolving shellac in de
natured alcohol. The best quality of shellac , called
button lac , should be purchased. There is no
special proportion of shellac to spirit (say 4 oz.
shellac to half pint spirit ). Make up the quantity
you expect to require — or more - put in plenty of
shellac, and allow it to soak for at least a day.
Stir the varnish weli, and try it by brushing some
on white paper. This will show if it is reasonably
thick ; the surplus shellac can be left in the solution
and more spirit added , if required, as the supply
diminishes. For best work the mixture should be
filtered or decanted so that the thick residue is
removed . Apply successive coats until a nice
amber tint is produced. Warm all glass before
varnishing until it can be just handled, also be
tween successive coats.
The sectors can be made of ordinary tinfoil or
thin sheet brass or copper. Any convenient num
ber may be adopted—the greater the number the
more readily the machine excites ; the less the
number the greater the spark length . It is not
advisable to have less than sixteen sectors on each
plate. To stick them on to the plates, use shellac
varnish . Make a drawing of the plate and sectors

MAKING AND MANAGEMENT 45
on white paper and lay plate over it. This will
enable you to stick the sectors correctly in position.
Some makers use a small button-shaped contact
stud on each sector. The object is to enable the
neutralizing brushes to make contact with the
sectors without scratching the surface of the plates.
These studs are not absolutely necessary and may
be dispensed with, as the brushes only require
to make delicate contact and can be composed
of very soft material. The ends of the sectors
may be covered with varnish for a small distance
to assist in holding them to the surface of the plate .
The sectors are to be stuck on the varnished sur
face , not directly on the glass.
Ebonite plates do not require a varnished sur
face. The thickness should increase with the
size of the plate ; about 1 inch for small diameters,
up to inch for large plates of 20 inches or even
larger diameter.
The bosses upon which the plates are mounted
should be bushed with brass tube. When fixing
the boss to the plate it is advisable to adopt some
form of clamping washer. As an additional pre
caution against slipping, stick the flange of the
boss to the plate with cement ; that which is used
cementing cycle tires will do — it may be obtained
from cycle repairers.
Two methods of clamping the plate to the boss
are shown by Figs. 11 and 12. That of Fig. 12

dispenses with cement ; a washer of very thin
rubber is placed each side of the plate to increase
the grip and provide a soft cushion to take the
strain when the nut is tightened. By this method
the plates may be removed easily from the bosses.
CIRCULAR
NUT
W
SHEET
RUBBER
WASHERS
FIG. 11 FIG. 12
In Fig. 11 the washer should be also cemented
to the plate . A simple method is to stick a flannel
washer against the face of the boss , then whilst
the cement is still soft coat the outer surface of

the flannel; press this against the plate until the
cement is dry. Fish glue , or any similar cement
used for mending glass, can be used. The flannel
washer constitutes a soft pad between the glass
and the wood , so that the plate is less likely to
crack in use .
+
B
B !
B
+ B
COLLECTING
COMBS
A A
Fig. 13
Distance Between the Plates. The more closely
the plates are together the better will be the
performance of the machine. This distance can
only be made a minimum if the plates run quite
true and are stiff.
The respective charges of electricity upon the
vertical quarters A A of the two plates (Fig. 13)

attract one another, being of different sign . Upon
the respective horizontal quarters B B the charges
are of like sign , and repel one another. If the
plates are made of yielding material they will be
pulled together at the quarters A A , and pushed
apart at the quarters B B by the attraction and
repulsion effect of the charges.
The neutralizing rods should be of metal , as it
is necessary for the two brushes on each rod to be
in metallic connection with each other. Each
rod must be set so that diametrically opposite
sectors are touched by the brushes. The rod
need not be insulated from the frame of the ma
chine as the brushes may be in connection with
earth .
The frame of the machine, though made of wood ,
is earth when considered in connection with static
electricity.
The brushes should be of very soft material, so
as to make very gentle contact with the sectors.
A bulky , stiff brush is not suitable ; it should be of
the character of a soft , open bunch of tinsel threads.
It is very important that the brushes are in good
metallic connection with each other.
The neutralizing rods should be clamped so that
they may be set at various angles , as the best
position must be determined by trial.

Round leather belting for driving the plates is
readily obtainable from engineers' supply stores
and sewing-machine repairers. The ends can be
fastened together by a wire link ; one belt of each
pair is to -be crossed to make the plate rotate in
the opposite direction .
The collecting combs and discharging rods must
be supported upon glass or ebonite of good insu
lating quality. It is of no use to make the sup
ports of wood , or to make the frame serve as a
support ; wood is useless as an insulator for this
kind of work . Leyden jars may be used as sup
ports when these are fitted as part of the machine .
The collecting combs may be made with several
points in a row so as to cover the length of a sector,
or a single point may be used facing any part of a
sector. Either arrangement seems to act equally
well ; the original machines were fitted with combs
having several points - not set to point directly to
the sectors, but slanted to a small extent with the
direction in which the sectors were moving.
All sharp edges or points should be avoided upon
the metal work of the collectors and discharging
rods to minimize leakage of electricity. The
inetal surfaces should be smooth ; ends of rods
should be well rounded or terminate in a ball.
If sharp edges or points exist , the charge is liable
to dissipate away as fast as it is produced . One
maker, actually encloses the metal parts with a
sheath of ebonite to ensure that the machine will

generate in a moist atmosphere ; there is no need ,
however, to take this precaution for ordinary
purposes.
Brushes should not be fitted to the collecting
combs ; no contact whatever is to be made with the
sectors at this part of the machine. The frame
of the machine may be wood or metal. If Leyden
jars are fitted as part of the machine, the outer
coatings of all should be in metallic connection
with each other. This may be done by wire or
metal strip. Frequently a switch is inserted in
this so that the metallic communication between
the positive and negative side jars can be inter
rupted.
Insulating handles should be fitted to the dis
charging rods for convenience of manipulation.
They may be of glass or ebonite. Each rod should
have a metal ball fixed to the discharging end ; they
should be of unequal size , a small ball being upon
the positive rod, and one about three times its
diameter upon the negative rod. The polarity of
the rods is found by trial ; the balls should therefore
be removable so that each can be placed upon the
proper rod accordingly. Brass -work may be
lacquered or not.
Leyden jars may be of any convenient pattern .
The size is determined by working considerations;
large jars will have greater capacity than smaller

ones , and affect the discharge accordingly . The
machine will work with them or without Leyden
jars at all. If you desire violent discharge of as
great a volume as possible , fit large jars. If you
desire as constant a discharge as possible , fit very
small jars or none at all.
Glass tube supports can be made to serve very
well as small capacity jars . The outer coating of
the jar can be tinfoil cemented on to the glass , or a
metal cup into which the glass jar fits. The inner
coating can be similar or consist of lead shot , the
jar being filled to the height of the outer coating.
Sulphuric acid would also do, in which case the
rod making contact with the inner coating should
be made of lead as far as it is immersed in the acid.
The covers of the jars should be preferably of
ebonite ; if of wood , it should be well coated with
shellac varnish to reduce leakage between the
inner and outer coatings.
In some patterns of Wimshurst machine no
sectors are fitted to the plates, which are perfectly
plain ; either ebonite or glass may be used. If glass
plates are used , they are not coated with shellac
varnish. These machines are a modification of
the Wimshurst , and designed by Bonetti with the
idea of increasing the output. The general con
struction is the same , but the neutralizing rods
are fitted with a line of brushes at each end to
cover a length of the plate approximately equal
to that which would have been taken up by the

length of the sectors if these had been fitted .
This is clearly shown in Fig. 10.
Instead of the collecting combs being fitted
with points, a single thin blade is fitted to face
each plate for a distance approximately equal to
the length of a sector in an ordinary Wimshurst
machine of similar size.
Management of Wimshurst Machines. The the
ory of the machine is briefly mentioned in Chapter I.
As the plates rotate , each sector takes away a
charge of electricity as it passes from contact with
a neutralizing brush . A distribution of electrical
charge takes place over the entire surface of each
plate . The neutralizing rods divide the surface
into approximately four quarters, as viewed from
the front of the machine . Two of these quarters
will be vertical and have sectors A A between
the rods (Fig. 13) . Two of the quarters will be
horizontal and have sectors B B between the rods .
Four sectors (C C on each plate) will be under
influence of the action caused by contact of the
neutralizing brushes. The charges on the sectors
A A of the respective plates will be of unlike sign .
For example , if the top sectors A of the front
plate are negative, the corresponding sectors of the
back plate will be positive ; the bottom sectors A
of the front plate will then be positive , and the
corresponding sectors of the back plate will be
negative . The respective positive and negative
charges will attract one another and be held in

place for the time being. The respective sectors B
on the front and back plates will, however, not
have unlike charges. If the front plate sectors B
in the left-hand quarter are positive , the cor
responding sectors on the back plate will also be
positive; the front plate sectors in the right-hand
quarter will then be negative , and also the cor
responding back plate sectors. The respective
like charges will repel one another, and they will
be under the influence of the collecting combs.
The respective charges will therefore be driven
away by this repulsion effect to the discharging
rods. At any instant the sectors A on each plate
can be considered as inactive , sectors C as under
going commutation , and sectors B as active . The
back neutralizing rod is shown in Fig . 13 by dotted
lines.
If the front plate is rotating in the direction in
dicated by the arrow , each sector passing away
from the top neutralizing brush will receive a
negative charge whilst in contact with the brush ,
and retain it until it reaches the collecting comb.
Each sector passing away from the lower neutraliz
ing brush will receive a positive charge, and retain
it until it reaches the other collecting comb . As
they pass the position of the neutralizing brushes,
the back plate each will act inductively upon the
sector being touched by the respective brushes,
and thus cause the sectors of the back plate to
take away positive and negative charges to each
collecting comb in a similar manner to the way in

which the sectors on the front plate are acting ;
the back plate rotating in the opposite direction to
that indicated by the arrow . The sectors on the
back plate reciprocate this action , and in their
turn induce charges upon the front plate sectors
whilst they are passing the position of the front
neutralizing brushes. Each one of the sets of
sectors thus alternately acts as an inductor and
a receiver, and the series continuing to pass the
brushes, the distribution of charge over the whole
as explained with reference to Fig. 13 , is main
tained . The important thing is to prevent leakage
of charge across the surface of either plate from
the sectors which have an active positive charge
to those which have an active negative charge , or
from either of these to earth . The surface of the
plates must therefore be kept free from moisture
and dust. Ebonite plates may, after a time , lose
their surface insulating property to a considerable
degree ; if this occurs , clean the surface with ethel
alcohol (not wood spirits) .
Neutralizing Brushes. The position of the
neutralizing brushes is important ; they should be
approximately as in Fig. 13 , but may be closed
towards the vertical, or opened further apart
according to results obtained . The machine is
likely to excite more readily with the brushes
nearer to the collecting combs, and to work
better afterwards if they are set nearer to the
vertical.

The speed at which the plates should be rotated
is indeterminate ; there is no given speed for any
particular size or number of plates — simply adopt
that convenient and at which the machine works
well. The spark length seems to be independent
of the speed , but the output increases with the
speed. If the machine fails to excite , try rotating
the plates in the opposite direction, also electrify
a stick of sealing wax by rubbing and hold it near
the sectors to induce an initial charge .
The collecting combs should be at equal distances
from the plates. All dust and moisture should be
removed from these parts and from the insulating
supports. If Leyden jars are fitted, the ends of
the discharging rods should be made to touch one
another before any of the metal work of the ma
chine is handled . This will discharge the jars
and prevent possibility of the operator receiving a
shock. The inner surfaces of the plates must be
perfectly clean and free from dust or oil. If the
machine fails to work, see to this. Also wipe all
dust and moisture from any part. The outer
surfaces of Leyden jars or supporting pillars
should be wiped clean and dry. The presence of
moisture in the air will affect the working ; best
effects will be obtained in a warm , dry atmosphere.
Some time and perserverance may be required
to get a machine to work if it has been from a cold
to a warm room . One of the good qualities of
the Wimshurst machine, however, is its reliability

to work under almost any conditions of atmosphere,
Machines having ebonite in their construction
should be kept in darkness or shadow as much as
possible ; sunlight has a bad effect upon the sur
face of ebonite, causing it to warp and deteriorate
in its insulating properties
.
Connections. When making connection by wires
or chains to any apparatus used for experiment
take care that they do not touch anything which
is not highly insulated from earth, or even approach
an earth -connected object within several inches.
Also be sure that such wires or connecting chains
have their ends in the form of balls or loops . If
the ends project so as to form a point, or approxi
mation to a point, the charge will leak away.
The Discharge. Though it is possible to take
the discharge by direct connection to the collecting
comb parts of the machine, this method may not
always be successful. It is advisable to fit spark
gaps and make connection through them . In
Fig. 14 the discharge is conveyed by the rods D D
to the terminals TT , to which the connecting
wires are attached. The ends of both rods and
terminals should be balls. The rods are adjusted
until the gaps G G are of sufficient length to pass
the discharge required by the apparatus. These
gaps would be used when taking shocks from the
machine, as from a medical coil. D D can be
the main discharging rods , or small ones auxiliary

to main dischargers ; this is a matter of arrange
ment . Fig. 14 is merely to show the idea of a
spark gap ; the actual details can be made to suit
individual cases. When illuminating X - ray and
ordinary vacuum tubes , the method of sending
the discharge through a spark gap should be em
G
lacno -T Toldobi
Fig. 14
ployed in preference to direct connection . The
terminal screws are shown with ball-shaped heads,
which are preferable for static purposes.
The positive discharger can be identified by the
sound of the discharge coming from it when the

58 THE WIMSHURST MACHINE ,
machine is working ; it gives off a hissing noise
when the balls are brought to within sparking
distance from each other.
In all probability a Wimshurst machine will
excite at once when first made and tried . The
polarity does not reverse under normal circum
stances , but may be changed if desired by the
following method. Disconnect the Leyden jars
if these are fitted to the machine ; bring the balls
of the discharging rods into contact . Rotate the
plates a few seconds in the opposite direction of
rotation ; separate the dischargers , and charge the
collecting comb of one side of the machine from a
Leyden jar which has been previously charged
from the other collecting comb—that is, if you
charge the negative combs, the jar must have been
previously charged from the positive combs.
Machines which have no sectors on the plates
(Bonetti system) do not self excite so readily as
the true Wimshurst machine with sectors. If
difficulty is found in making such a machine to
excite , try rubbing one of the plates to produce an
initial charge.

CHAPTER IX .
SOME EXAMPLES OF WIMSHURST MACHINES.
SMALL MACHINES.
The following designs of home-made Wimshurst
machines are selected as suitable examples for ama
teurs to make, and show that avery modest amount
of skill and expense is sufficient to produce a ser
viceable and successful machine. The first ex
ample , shown in Fig . 15 , is a miniature two -plate
machine.
The Framework is 41 in . long by 3 in . wide ,
made of boxwood in . by 1 in . The end pieces
are fixed by screws at corners from underneath .
The standards are 5 in. high , 1 in . wide at bottom ,
tapering to 16 in . at top , and are mortised and
glued into framework with holes drilled near top
and bottom to take the plate and driving spindles ,
the former being kept in place with round -headed
setscrew on top of standard, bearing on a flat
filed on spindle . For drilling the various holes ,
I used Morse twist drills for metal, which cut
well and prevented the wood splitting.
Plates are 3 in. in diameter by in . thick.
They were made by screwing a sheet of ebonite
to a wooden face plate , boring a fin. hole in the
59

centre and facing edges of hole squarely. Put
into a lathe and cut to size with a narrow parting
tool for brass . The edges were then rounded
with a fine file, smoothed and polished with fine
glasspaper and brickdust and water ; while on the
faceplate a circle 21 in. diameter was slightly
scratched on one side of each plate . This was di
Fig . 15
vided with compasses into sixteen equal parts , and ,
on removal from lathe , radial lines were drawn
through these points and thin tinfoil sectors, & in .
long , 4 in . at widest end , and } in . narrowest end ,
were fixed with very hot strong solution of car
penter's glue , centrally on each radial line , giving
a ring of sectors in . from the edge of plates .

SOME EXAMPLES OF WIMSHURST MACHINES 61
Plate Bosses. · These were made of boxwood
turned to shape as shown in the illustration , the
wood was then bɔred and mounted on a knitting
needle , in , in diameter, as a mandrel, pulleys
turned to in . diameter with V -groove and other
end carefully shouldered and fitted to hole in ebon
ite plate , which enabled the plates to fit squarely
and to run true. They were secured in place with
a little Prout's elastic glue. A knitting-needle, a
shade smaller than the one used for mandrel, I
used as spindle for plates and bosses to revolve on .
Driving Gear. A knitting-needle, $ in . diameter,
forms the axle ; a piece of beech was driven on to
form a sheath , turned to shape and both ends
shouldered . Two beech pulleys , 2 in. diameter by
in. thick , bored } in . to fit ends of sheath , and a
V-groove formed on edges to correspond with
pulleys on bosses , were then gluer on shouldered
ends of sheath , and the whole finally trued in lathe.
One end of axle is threaded for f in . , and a brass
crank fitted with revolving handle attached. To
centre knitting-needles to run in lathe , I cut them
to length , then carefully ground ends to a cone ,
then mounted them between female centres with
which my lathe is fitted, and with a little patience
in the grinding got them to run very true.
The driving belts are of 1 in . tape , folded longitu
dinally and ends sewn together. I find these grip
well and do not stretch much .

Prime Conductors. In the absence of proper
brass balls for conductors, I used two " sparklet "
soda-water syphon bulbs , which , after drilling, and
drifting out the plug in neck , I fixed on varnished
glass rods with elastic glue . The lower ends of
rods are fixed in wooden sockets , glued to frame
work . A 1 in . hole is drilled in top of each bulb
to carry the curved discharging rods of stiff copper
wire furnished with brass knobs on outer ends.
The collectors are of similar wire bent U-shape.
A it in . cycle ball (previously softened and drilled)
is soldered at each end of limbs. A row of three
pin points is fixed in fine holes drilled in sides of
the U's. These collectors are soldered at the
bend in grooves filed in the sides of bulbs to give
a strong joint.
The neutralizing rods, also of copper wire, are
bent as shown in photograph, and are fixed to
projecting ends of plate spindles by a small brass
boss with setscrew. To their ends are soldered
brushes of fairly springy fine copper wire , obtained
from a piece of flexible electric light cord , and are
set so as to gently wipe the tinfoil sectors as plates
revolve. All the metal work was polished and
lacquered. The plates are kept apart about
it in . by a thin ebonite washer threaded on the
spindle.
When all is dry and warm , the machine excites
at once and gives a continuous stream of 1 in .
-

sparks . It will work four 4 in. vacuum tubes very
well, charge small Leyden jars , giving quite à
smart shock, and answers well in performing all
Fig. 16
the usual experiments carried out with this class
of machine , though , of course, on a small scale .
Fig. 16 shows a small machine specially designed

for compactness, and only occupies a space of
9 in . wide by 7 in . deep .
The plates which were cut out of sheets of ebon
ite f in . in thickness are 9 in . in diameter, and are
mounted on mahogany bosses , fitted with brass
bushes to ensure easy running. There are 24 sec
tors of copper foil on each plate , but I do not re
commend this material for the purpose, as the edges
do not stick to the plates firmly , and the electricity
dissipates into the air. The plates run about it in .
apart, but unless suitable wedges are inserted
when the machine is not in use , they touch.
The Leyden jars are coated inside and out with
thick tinfoil, with shot to make the connection
inside. I have not varnished the glass with any
insulating material
, nor have I found the efficiency
of the machine impaired thereby.
The metal work on the machine is of gunmetal,
polished and lacquered , and looks very well.
Under ordinary circumstances there is no diffi
culty in drawing a 2 in . spark, but in a warm room ,
when the machine is well up to its work , I get a
stream of 4 in . sparks .
A simple machine is shown in Fig . 17 , having
two plates of ebonite 10 in . diameter by } in . thick
The bosses are made of two ordinary cot
ton wheels, one end being cut off and a V -groove
cut in each for driving. Two pieces of brass tub
ing were fitted inside the reels; a thin brass washer
ness .
-
-

-
was first soldered to one end of each piece , and
threads cut and nuts fitted to the other ends.
When in position the washers grip the plates
against the face of the reel, making the whole firm .
Fig. 17
The spindle for the plates is of steel, } in. diam
eter, and for the driving pulleys in . diameter.
The driving pulleys are 34 in . in diameter, made
from wooden wire bobbins. A deep V-groove was

first cut with a knife and finishing touches given
with a rat- tail file, the whole being firmly held on
the shaft by a screw running through the centre
of bobbin.
White metal bearings were made for the driving
pulleys, which run quite silently and without any
shake.
Collectors, neutralizing rods, and dischargers are
all made from ſ in . copper rod. Pieces of brass
were fitted with screws and soldered to the centre
of neutralizing rods. The screws grip the projecting
ends of steel spindle, enabling the rods to be set
at any angle. The same plan was adopted for fixing
the collectors, and is very convenient.
Leyden jars were made from two ordinary pint
bottles cut close to the neck and coated inside and
out with lead foil to a height of about 3 in . A
cotton reel was cut in halves and each half fitted
with a } in . brass tube through centre , 2 in . of
tube being left projecting. The half reels were
placed in the necks of bottles , the large ends of
the former being just large enough to prevent them
slipping inside. Hot compound was run between
the necks and the reels.
To fix the Leyden jars to the base, circles 1 in .
larger than diameters of jar were cut out of two
squares of wood (34 in. by 37 in . by * in.) . Strips
of stout brown paper were cut and glued in the

SOME EXAMPLES OF WIMSHURST MACHINes 67
form of a narrow cylinder 1 } in . wide, the jars
being used as a size. The paper cylinders were
then glued into the circles cut in the squares of
wood. The latter being then screwed to the base ,
not the slightest movement of the jars is possible.
The collectors slip over the brass tube projecting
from the Leyden jars , and can be fixed at any
height by screws, as in the case of the neutralizing
rods. The rods for the dischargers are an easy fit
inside the tubes , enabling balls to be revolved and
the spark length varied.
The stand is 16 in . by 6 in . , and the supports
9 in. high , painted black.
The machine will excite instantly in any weather,
although the results are slightly better when the
weather is quite dry. It will be noticed that the
only balls used are on the dischargers. This does
not seem to affect the efficiency of the machine to
any considerable degree.

CHAPTER X
A LARGE WIMSHURST MACHINE .
For many months I have devoted my attention
to the design and action of the Wimshurst ma
chine, and have studied with interest the various
forms described in the text-books and magazines
devoted to the science. Up to the present , how
ever, I have failed to find a design which fully
came up to my own idea of an ideal Wimshurst ,
one which would be equally adaptive to scientific
experiment and practical use. I therefore de
voted my own energies to the design of a machine
which would fill these requirements, and, after
much forethought and experiment, succeeded in
completing the machine which is here described
and fully illustrated. I believe it is absolutely
necessary that the scientist's electrical machine
be somewhat portable , as there are many occa
sions on which it has to be taken from place to
place—as , for instance , when lecturing, exhibiting,
etc. We then find how inconvenient one of these
machines is to take with us , the brittle plates , etc. ,
preventing one from packing the apparatus suffi
ciently well to ensure its safety during transit.
I have therefore kept the matter of portability in
view throughout the entire construction, and de
signed the various parts accordingly. (Figs. 18-24.)
68

A LARGE WIMSHURST MACHINE 69
ma
1
1
7
Front Elevation.
Collectors.
I full size.
Brackets
for Standards. FIG. 18.

The size of machine I selected --24 - in . plates
is rather large, but all the parts are of first-class
construction . The initial cost of making may
somewhat exceed that of the machines usually
described, but from experience I would urge all
those who really can afford it, and who are about
to construct an influence machine, to make all
the parts according to instructions given . As a
result, the maker will be in possession of a genuine
first -class influence machine worth a dozen make
shifts .
Apologizing for this somewhat lengthy intro
duction, I shall now proceed with the practical
part of my subject, and shall first describe the con
struction of the various parts, and then follow
with instructions for putting the parts together.
The stand is of walnut, dovetailed at the corners,
the top being secured to the frame by means of
screws and corner -pieces from beneath. It will
be as well to leave the boring of the holes in the
top till further on.
The standards are also walnut, and have two
Le in. holes bored to receive the driving and plate
spindles. One hole has its centre 34 in. from the
bottom of the standard , and the other 11 in. from
the top. Both holes are bushed with i in. brass
tubing, is in . in substance. The standard sockets
are cast in brass to finish f in. thick - b has two
projecting lugs at the bottom ends in . thick, and

frd full size.
Left Hand End Elevation.
Bases for Leyden Jars. Standards.
Fig . 19.

a has one similar lug projecting from the centre .
These lugs have it in . holes bored near their ends
to receive clamping bolts.
The driving apparatus consists of a ja in . silver
steel spindle, 157 ins. long covered by the hard wood
sheath which bears on its ends the wheels. The
sheath is bored in the lathe previous to turning
up , and fitted with the steel spindle . The spindle
is then centred in the lathe , and the sheath turned
up to shape and dimensions given . The wheels
should be cut as nearly round as possible , and the
17 in . holes bored in their centre , and finally glued
to the shoulders on the sheath . The spindle is
then again centred in the lathe and the wheels
turned up to shape .
The pieces from which the plate bosses are to
be turned up should have it in . holes drilled in
them , and then bushed with a piece of perfectly
true brass tubing 1 in. diameter, 1 in . in sub
stance . Now run a Bs in . drill through the hole in
the brass bushing to ensure its being true. Place
on a mandrel, and turn up the boss to shape. It
should be observed that the bushing of the bosses
should protrude to in, at either end of the boss.
The plates are 24 ins . diameter, 16 oz. “ patent
plate ” giass , with central hole in . diameter.
This kind of glass may be obtained from most
large glass merchants , and is the only sort that
can be relied upon for truth in flatness. The ordi

Plan of Wimshurst Machine.
TL
Fittings for Prime Conductor.
Fig . 20.

nary sheet or window glass often recommended
for this purpose is practically useless, as it is im
possible to obtain a piece which is of equal thick
ness throughout, or which , when mounted on the
bosses, will run perfectly true. As a consequence,
we must keep our plates f in. or more apart, and
thereby reduce the power of our machine consid
erably. I would advise the reader to have his
plates drilled in the house where he buys them, as
I believe glass is not a proper thing for novices to
practise on . The plates, cut circular and bored ,
can easily have their edges ground by rubbing them
with an old emery disc , which may be had at any
engineering works for the asking. Use plenty of
water with the disc when grinding the plates.
The bosses are attached to the plates with fish
glue spread on thin flannel washers . Cut out two
washers from thin flannel the same diameter as the
large end of the bosses, and with central hole
about 1 in. diameter. Well cover the side of the
washer with the glue and press firmly down upon
the face of the boss . Now smear some more glue
over the dry side of the flannel washers , and allow
them to dry for about ten minutes. They should
now be pressed up to the plates and given a slight
twist to ensure the glue spreading evenly over
the entire surface of that part of the plates covered
by the bosses. The plates should now be removed
to a flat surface, and a weight placed on the top
of the boss so as to maintain a slight constant

A LARGĘ WIMSHURST MACHINE
75
1
Strengthening
Pieces
for
Cover
.
Right Hand End Elevation.
Corner
Supports
for
Cover
.
Brass Hook for Prime Conductor.
Fig. 21 .

pressure until the glue sets , which will take about
six hours . I would here warn the reader not to
fasten his bosses to their plates without the
flannel washers , as the plates would surely crack
during rotation .
The next operation is to fit a te in . ebonite
washer to the inside face of one of the plates.
This washer should be about 2 ins. diameter, with
a central hole fin . diameter, and is fixed to the
plate with the glue mentioned above . The plates
can now be varnished with good shellac varnish ,
as a half pint will be more than sufficient for all
parts requiring this varnish . A great deal depends
on the purity of this varnish, as the insulation in
creases with the purity. Warm the plates evenly
all over, and apply the varnish with a broad camel
hair brush . Always draw the brush in the same
direction , and do not go over the same place more
than once .
The sectors of which there are 32 on each plate,
are of tinfoil, and are stuck to the plates with
thick shellac varnish or thin glue. To fix these
sectors to the plates evenly, strike out a circle of
24 ins. diameter on a sheet of paper. From the
same centre strike out another circle 224 ins . diam
eter, and divide the circumference into 32 equal
parts. From these points draw lines to the centre .
Now place the plate on the paper , see that the
edge of the plate lies evenly on the circumference
of the 24 in, circle, and fix the sector over each of

A LARGE WIMSIURST MACHINE 77
"Brass Elbow.
įrds full size.
Sheath
and
Driving
Wheels
dth
full
size
.
Sockets
for Cover.
Driving Crank.
ith full size.
Prime Conductor.
Fig . 22.

the lines drawn on the paper, the wide end of the
sector just touching the circumference of the in
side circle drawn on the paper. In this way the
whole 32 sectors are placed evenly and equi
distant on the plates , and a clear margin fin.
wide left between the top of sectors and edge of
plates.
The driving bands are continuous round rubber
rings, 8 ins . diameter, 4 in . thick . These bands
are preferable to leather, as no means of tightening
is necessary, the stretch which must be given to
them in order to bring them over the bosses serving
to maintain a constant hold on the wheels and
bosses during use.
The neutralizing rods are 4 in. brass bent to
shape and screwed into the holder. The brushes
are made from tinsel wire, and are secured in an
in . hole in the ends of the neutralizing rods by
means of a little wooden peg. The rod holder,
which has a saw-slit the full length of the barrel,
is made from a casting and finished in the lathe.
The hole in the barrel is in . in diameter, or
} in . less than the plate spindle. The saw -slit
enables us to press the holder on to the projecting
ends of the spindle, upon which it should have a
firm grip.
The jars are 14 ins . high , 21 ins . diameter, and
mouth 2 ins. diameter. The tinfoil coating on the

Neutralising Rods.
1
Base for Prime
Conductor Support.
Plate Bosses.
ath full size.
jrds
full size.
Double Connector.
ird full size.
Leyden Jar Rod Holders.
frds full size.
Fig. 23.

outside is 3 ins . deep , and the inside is filled with
gunshot to the same height. The outside, bottom
of the jar should be entirely covered with the foil,
and the coating of the sides overlap the bottom
edge about 7 in . All uncovered portions of the jar
must be well varnished with good shellac varnish .
The cover of the jar is a disc of boxwood in . thick ,
with rounded edge. To one side of this disc is
glued, with fish glue , a new cork bung, which fits
the jar mouth . Bore a } in . hole in the centre of the
wooden disc , and continue this through the bung
with a cork borer. Bush the hole with a piece of }
in . ebonite tubing, and allow this to protrude about
1 in . below the bottom of the bung.
To the top of the boxwood discs are screwed the
rod holders with small round-head brass screws.
This holder, which is made from a casting, must
be well finished in the lathe, and have all edges
carefully rounded . In the side will be seen a ball
head adjusting screw . If any difficulty is experi
enced in procuring these screws, they can be
easily made by screwing a short piece of me in .
hard brass wire into a fin . brass ball, and then
running a thread on the piece of wire which pro
jects . A corresponding hole will have to be drilled
and tapped in the holder to take the adjusting
screw.
The jar rods are 12 ins. long, in . diameter,
furnished with a 14 in. ball on their upper ends,
and 4 ins. of brass contact chain on their lower

-2% * 23 "
-0
CENTER OF PLATES
20
"
-
WIDE
-6/4 ". * .-64".
142% * 29642
31- + LONG
-824 " 82 "
Baseboard.
Cover.
Discharging Handles frd full size.
Fig . 24 ,

extremity. This chain is a light brass wire chain ,
made specially for the purpose of making contact
with the interior coating of Leyden jars. The brass
ball has a hole drilled through the centre and tapped
to receive the collectors and connecting rods.
The connecting rods are it in . brass, bent to
shape . The extremity of the rods have a thread
run on them for a distance of fin . to enable them
to be screwed into the balls on the jar rods. · The
collectors are also it in. brass rod, bent thrice at
right angles. The parallel sides have four points
fixed on their opposite faces . These points are 1
in. brass tacks , with their heads removed, and are
screwed into the rods about } in . On the free end
of the collector rod is screwed a fin . brass ball,
and on the other end is run a screw thread for a
distance of fin . The collectors are screwed into
the opposite side of the jar rod balls to that into
which were screwed the connecting rods .
The jar bases are of walnut. The top is sunk
in . to take the jars , and in the centre is bored a
fin. hole to take a piece of ebonite tubing. Half
way between the centre hole and the wall of the
base is bored a fin . hole to take a small clamping
bolt . This latter hole should be countersunk. A
disc , 21 ins . diameter, should now be cut from
3. in . sheet brass . To the centre of this disc is
soldered a piece of No. 20 copper wire , about 6 ins .
long , bent on itself to form a narrow U 3 ins, long.

A LÁŘGE WIMSHUŘSŤ MACHINE 83.
It is the ends of the wire which are soldered to
the brass disc, and when the solder has set the
wire should be twisted to within 1 in . of the bot
tom , thus leaving a small loop.
а.
The discharging rods' insulating supports are
in . ebonite rod or tube 113 ins. long, fitted with
brass fittings. The bottom fitting has a piece pro
jecting from underneath , upon which is run
screw thread. A butterfly nut must fit this screw
for clamping the supports to stand. The upper
fitting has a hole 1 in . diameter drilled all the
way through the horizontal arm to take the dis
charging rods , and both upper and lower fittings
have } in . holes drilled in their barrels to admit
the insulating -rods. These latter holes should be
bored 2 ins. deep . In the top centre of the ball
head is bored and tapped a hole, into which is
screwed a } in . connecting rod, about 41 ins.
long, furnished at its upper extremity with the
ball-screw double connector. The discharging
rods are 12 ins. long, in. diameter. To one end
is fixed the insulating handle , and the other is
fitted with a brass ball. The right-hand or nega
tive rod has a 2 in. ball , and the left -hand or
positive rod a in . ball. These balls should be
fixed to the rods by screwing, but must not be
fitted until after the rods have been passed through
the holders.
The insulating handles are walnut with ring-end
ferrules, and must be soaked in melted paraffin wax

for about twenty -four hours. They should then
be held vertically by their ferrules and lifted
quickly out of the liquid. Allow the thin film of
wax to set, and , still holding vertically , again im
merse in the paraffin and immediately remove.
Repeat these operations about four times, per
mitting the wax to set after each removal from the
liquid. A thin layer of wax will thus be formed
uniformly over the entire surface of the handles,
which will greatly increase their insulating prop
erties, and, if done properly, at the same time im
prove their appearance.
The prime conductor is made from 12 ins. of
1 in . brass tubing, into the ends of which are
sweated the two 23 in . brass balls seen in the
figure. In the centre of the tube is screwed the
socket. If both the tubes be heated over a blow
pipe or Bunsen burner, and a little solder allowed
to flow over the screw thread, and the socket then
screwed and sweated into the larger tube , greater
strength will be obtained than by screwing the
two together, very few threads being possible on
the thickness of the larger tube. At right angles
to the socket, and in the centre of the conductor,
is screwed the it in. brass grappling hook. This
hook is terminated with a 1 in . brass ball.
The finished conductor should now be mounted
on the insulating pillar. This pillar is ebonite,
fin . diameter, 15 ins . long , and should be fastened
in the socket with electrical cement , as should

also the discharging rod supports mentioned above.
The bottom end of the support is fitted into the
base . This base , which is of walnut, has a fin.
hole bored in it 14 ins . deep , to receive the sup
port, and the hole then continued with a 1 in.
bit right through the bottom . Countersink this
4 in . hole on the inside , and pass a } in . bolt through
it. Before fixing the support, pass it through a
collar, keeping the ring end uppermost. Now
cement the support into the base, and when the
cement has set, allow a small quantity to melt
round the support just where it enters the base.
Press down the collar, give it a slight twist, and
allow cement to set.
The cover of the machine is made from green
baize, sewn together at the corners and all round
the top. A seam about ſ in . wide should be left for
binding with a braid same color as the baize . As
it is necessary that the cover should sit squarely
over the machine , four supports will be required
at the corners . These supports are fin . walnut
rods, tapered to in. at the top. These are fitted
with brass sockets at their lower ends, to enable
them to be clamped to the stand. The sockets
are 11 in. brass discs, zin . thick , soldered to i in .
diameter brass tube 2 ins. long. In the centre of
the disc is bored a } in. hole, and through this hole
is passed a f in . bolt. The rods are then fastened
in the sockets, and a small thumb nut provided
to fit the fin , bolt.

If desired, the reader could also have the cross
pieces. These are walnut rods, fitted at their
ends with brass elbows , and can be pressed down
upon the tops of the cover supports , and thus pro
vide additional support for the cover at the ends.
The crank is made from a casting and screwed
into the end of the driving spindle, which should
have a thread run on both its projecting ends, so
that the handle may be fixed on either end.
The actual making of the parts is now com
pleted, but some advice on the finishing will be
necessary. The bosses , jar bosses , jar bungs , and
prime conductor base should all be soaked in molten
paraffin wax for several hours previous to French
polishing. Every brass part which takes an active
part in the working of the machine should be
deprived of all sharp edges, a nice round being
given to every angle. A good point to bear in
mind is to have neither roughness, scratches, sharp
edges, or points on any working metal part but
the collector points, and to have every one of these
latter covering some portion of the sector when
brought opposite to it, taking care to have no
points outside either end of the sectors. The
brass must be brought up to the finest possible
degree of finish , and then well polished. The pol
ished surface is then treated in the following man
ner previous to lacquering. Make a pickle of from
5 to 10 parts of sulphuric acid to 100 parts of water.
Into this bath the articles are placed till all grease,

discoloration , oxidation , etc. , is removed. They
should now be strung on wires and dipped into a
bath of nitric acid .
Care must be exercised in the selection of the
nitric acid, as there are several qualities in the mar
ket. An acid of a pale straw yellow is preferable ,
and if a little sawdust is added it will help the
acid. Before dipping the articles to be lacquered,
the acid must be diluted with water. If one im
mersion does not make the brass bright enough,
it will have to be thoroughly washed in clean run
ning water, and again dipped in the acid bath .
When they have been dipped, the parts are dried
in hot sawdust. Iron must not be used for any
purpose in any of the foregoing operations, as it
discolors the brass.
The lacquering of the articles requires a little
experience to do it properly. For this purpose an
iron pan of any convenient size should be procured
and placed upon an iron support. Beneath the
pan is placed a Bunsen burner. On the pan are
placed the articles to be lacquered, and they are
allowed to remain until they are at the heat of
boiling-point . The lacquer is then spread over them
with a flat camel-hair brush . This should be done
lightly and evenly, so that the work may appear
regular when finished . The heat of the articles
drives off all moisture and evaporates the spirit
contained in the lacquer. If the work is too hot,
it will oxidize ; if too cold it will appear streaky,

and the lacquer will not set properly. The lacquer
known as pale gold will give the best appearance
to brass for scientific instruments. Green also
gives a good finish , and is often used by instrument
makers.
Bronzing. A few of the brass fittings may
with advantage be bronzed. The discharging
rods and balls and crank will all be improved by
bronzing . Having dipped the articles into the
nitric acid bath and well swilled them in water,
they should be placed in the following mixture
until they have assumed the desired tint. Take
one part nitrate of tin , and add two parts chloride
of gold dissolved in a little water and acid. After
removing from the bath , wipe the articles with a
clean linen rag . It should be observed that the
articles should be polished with rottenstone pre
vious to being immersed in the bronzing bath .
Some experience will be necessary in order to
lacquer or bronze satisfactorily , and I would
advise the reader to test his skill on a few pieces
of brass before taking in hand the more important
articles belonging to the machine.
Every wooden part of the apparatus should be
well French -polished with the exception of the
boxwood discs on the jar covers , which should be
coated with shellac varnish . Every part of the
machine should be entirely finished before fitting
to another part, and great care will require to be
taken to prevent electrical cement flowing over

any part of the brass work when fixing in the insu
lating pillars, etc. , as this would require the brass
to be scraped in order to remove it.
Assembling. Having completed the parts, pro
ceed to fit them together. Commence by screwing
the standards to their sockets. The plate having
the two lugs is screwed to that side of the standard
which will be away from the driving wheels, and
the plate with the single central lug, to the side
nearest to the driving wheels. The driving bands
are now thrown loosely over the driving wheels,
and the ends of the driving spindle passed through
their holes in the standards. The standards are
then bolted to the stand with brass bolts passing
through the socket lugs , and screwed up with
thumb-screws from underneath the stand. Take
up the plate-spindle, and holding it in the top hole
in one of the standards, pull up a driving band and
place it over the spindle end. Next pass the spin
dle through the boss and plate, and, holding the
other plate close up to the first, push the spindle
along until it comes through at the other end of
the boss. The second driving band is now pulled
up , given a single twist, and lifted over the end of
the boss . The spindle can now be passed through
the hole in standard No. 2, and if two flats have
been filed on those parts which lie inside the holes
in standards , a round head brass screw inserted
from the top and screwed down upon the flats
will keep the spindle from turring when the ma

chine is in motion . The jar bases should now be
clamped to the base by small bolts passing through
the smallest holes in the base and stand. The larger
central holes in the bases must correspond to the
larger holes in the stand . Through these holes,
which should be bushed with a piece of ebonite
tubing long enough to extend about 1 in . through
hole in stand, passes the twisted wire soldered to
the brass disc. A disc of ebonite , si in . thick,
inserted between the brass disc and the base, im
proves the insulation of the former. The two
twisted wires should be connected by a guttapercha
and double silk-covered copper wire. The ends
of the wire should be bared of their covering for
about 11 ins . , then passed through the small loop
at the end of the twisted wires protruding through
the top of the stand, then bent back on themselves
and well twisted . Lap the bare portions of both
wires with a piece of silk tape immersed in paraffin
wax .
The jars can now be fitted to their bases, but
before doing so the collectors and connecting-rods
should be screwed into the brass ball on the jar
rods. The discharging-rod supports should now
be fixed in position , and clamped with the thumb
screws. The rods themselves can then be passed
through the holders , and the balls afterwards
screwed to the ends. The free ends of the con
necting-rods, which we screwed into the jar balls,
should now. be inserted in the upper end of the
double connectors , on the top of each of the sup

port connecting-rods. These rods are clamped
in the connectors by means of the ball screws ; the
neutralizing rods being screwed into their holders,
are fitted to the projecting ends of the plate
spindle. Let us imagine the plates to be the face
of a clock, and let us stand facing the front, or
that side of the plates nearest to the jars. The
rods on this side of the face of our imaginary clock
will point to XI and V, and that on the other side
to I and VII .
In giving these directions , it has been assumed
that the handle of the machine will be screwed to
the end of the driving spindle at the front of the
machine, and that the person using the handle is
a right-handed person , and will turn the handle
to the right in the direction of the hands of a
clock. If, however, we desire to screw the handle
to the back end of the driving spindle, the position
of the neutralizing rods will require to be re
versed. Turning the handle to the left will also
necessitate the reversal of the brushes, unless it
is screwed into the back of the machine, in which
case the position of the brushes will remain the
same as that given above .
When the machine is in good working order the
left-hand side of plates, collectors , and dischargers
will be positively electrified, and those on the
right-hand negatively electrified. If we reverse
the directions of motion , and consequently the
position of the brushes, the electrical condition of
the machine will also be changed, positive elec

Winmshurt Machine Patente1908i.pdf

Winmshurt Machine Patente1908i.pdf

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Winmshurt Machine Patente1908i.pdf