The document provides a detailed overview of the history and development of units of measurement of time. It discusses early natural methods of telling time based on the sun and moon. It then outlines the evolution of early timekeeping devices from sundials and water clocks used in ancient Egypt and China, to the development of mechanical clocks in Europe in the 13th-15th centuries powered by weights and springs. It further describes atomic clocks developed in the 20th century which use the vibration of caesium atoms to define the international standard second. The document concludes with the modern understanding of time in Einstein's theory of relativity.

1. ASSIGNMENT TOPIC: UNITS OF MEASUREMENT OF TIME AND THEIR DETAIL
Name Hafiz M Waseem
ROLL NO. Mcf-1901171
Semester 2nd (E)
Department Zoology
Subject Biological techniques
Presented to Sir Arshad sab
Presented date 22-06-2020

2. Contents
History
Defination and unit
Natural events
Sun base moon base Earth
base units
Sundial
Sand glass
Water clock
Oil lamp
Candal clock
Spring power clock
Cesium atomic clock
Digital clock
Harmful effects
Manofacturing process of a
clock
Refrences

3. The division of our day
into hours and minutes
predominantly to Ancient
Egyptians
They were the first to
develop devices of time
keeping
History

4. History of Egypt
Tomeasure when the Nile flooding, which threatened the entire country, took
place, Ancient Egyptians invented ways to "keep" time.
Since their agricultural system depended on time
keeping, a calendar would help them to determine the flooding of the Nile,
which was essential for their farming practices.
Egyptians invented different types of clocks in order to measure time.They
used different types of clocks; the shadow clock and the water clock

5.  It defined As About 9 Billion Oscillations Of The Caesium Atom.
In classical Physics it is a scalar quantity
In the International System of Units (SI), the unit of time is the second.
It is defined by taking the fixed numerical value of the caesium
frequency ∆νCs,
It is a SI base unit, and it is currently defined as "the duration of 9 192
631 770 periods of the radiation corresponding to the transition
between the two hyperfine levels of the ground state of the caesium
133 atom".
This definition is based on the operation of acaesium atomic clock.
Defination of time and their unit

6. Measurement of time
Natural event
The earliest natural events to be recognised were in the heavens, but
during the course of the year there were many other events that indicated
significant changes in the environment.
 Seasonal winds and rains, the flooding of rivers, the flowering of trees and
plants, and the breeding cycles or migration of animals and birds, all led to
natural divisions of the year, and further observation and local customs led
to the recognition of the seasons.
 As the technology of glass-blowing developed, from some time in the 14th
century it became possible to make sandglasses
In the past when there were no clocks people used water clock, the hour
glass, candle clock and sun dials.

7. Sun based Moon based and Earth bssed units
1)Sun-based
theyearwasthetimefor theearthto
revolvearoundthesun.Year-based
units include
theolympiad (four years),
 thelustrum(five years),
 theindiction (15years),
thedecade,
the century,and
the millennium.
2)Moon-based:
the month wasbased on the moon's
orbital period around the earth.
3)Earth-based:
the time it took for the earth to rotate
on its ownaxis,asobserved on a
sundial.

8. The Sundial
 The sundial was created in 3500 BC and
was the first instrument to measure time.
 It was also the oldest scientific device.
 The sun creates the shadow on the
sundial that can be used to tell what time
it is
 As the sun moves across the sky, shadows
change in direction and length,
 so a simple sundial can measure the length of
a day.
 It was quickly noticed that the length of the
day varies at different times of the year.
Measurement of time

9. Hour Glasses or Sandglasses
The was created some time in the
14th century. The sand falls through
at a certain rate so people can be
able to know how much time is
passing. Different sized hourglasses
are used for different amounts of
time.
 As the technology of glass-blowing
developed, from some time in the
14th century it became possible to
make sandglasses.
Measurement of time

10. Water clock
The water clock was created in 325 BC and one
of the first clocks that was ever made.
 Water would drip down at a constant pace and
collect at the bottom of a bowl that had markings
on it to tell what time it was.
 it a device which relied on the steady flow of
water from or in to a container.
 Measurements could be marked on the
container or on a receptacle for the water.
 In comparison with the candle or the oil lamp,
the clepsydra was more reliable, but the water
flow still depended on the variation of pressure
from the head of water in the container.

11. Oil Lamps and Candle Clocks
Oil Lamps
There is archaeological evidence of oil lamps about 4,000 BCE,
 the Chinese were using oil for heating and lighting by 2,000 BCE. Oil
lamps are still significant in religious practices, symbolic of the journey
from darkness and ignorance to light and knowledge.
 It was possible to devise a way of measuring the level in the oil
reservoir to measure the passing of time
 Candle Clocks
Marked candles were used for telling the time in China from the sixth
century CE
. There is a popular story that King Alfred the Great invented the
candle clock, However, the rate of burning is subject to draughts, and
the variable quality of the wax.
 Like oil lamps, candles were used to mark the passage of time from
one event to another, rather than tell the time of day.

12. Measurement of time
Galileo was the first scienciest and
replaced all the divices by clocks
and divices.
Some of them are so accurate that
they are beyond our imagination.
 This type of clock needs to be
stationary in order to work
properly because motion causes
time in accuracy
 Mid 1720s – John Harrison
improved accuracy of pendulum
clock to 1/5 second per day.

13. Foucault's
pendulum in the
Panthéon of Paris
can measure time as
well
as demonstrate
the rotation of
Earth.

14. The First Spring Powered Clock
 The spring-powered clocks were invented in 1500.
 At the time it was a revelation because it was small
and portable.
 It was a large improvement, but it still did not even
have a minute hand.

15. Digital Clock
The digital clock shows a numerical representation of the current time.
It was developed in 1972 by a watch company named Hamilton.
There are two display formats used for this kind of clock.
24 hour notation which range from 0-23 and 12 hour notation, with the
AM and PM indicator.

16. cesium atomic clock
To measure any time interval we need a
clock
We now use an atomic atomic standered of
time.
It is based on periodic variation
It produce in a cesium atom
it based on periodic vibration produce in
cesium atom
This is the basis of cesium clock
Sometime called atomic clock
Use in the national standered

17. cesium atomic clock
In the cesium atomic clock second is taken
as the time needed for 9,192,631,776
vibration of radiation
It corresponding to the transition between
two hyperfine levels of ground stste of
cesium -133 atom
The vibration of cesium atom regulate the
ratr of cesium atomic clock just as the just
as the vibration of atomic balance wheel
regulate

18. Harmful Effects
 Some clocks are coated in
radium, which is a radioactive
chemical. This material can
harm you if it comes into contact
with your body.

19. Measurement of time

20. Measurement of time
Time also has units like year, month, day, hour etc.
Thus length has units like kilometer, meter, cetimeter,milimeter etc.
Time also units like year,month,day, hour, etc.

21. Measurement of time
Millenium 1000 years OR 10
Century
Similarly one century has 100 year
One second is smallest unit of time
that we can see in clock and watch
by clicking

22. • .
The Manufacturing
Process of a Clock

23. modern conception of time
Both Galileo and Newton and most people up until the 20th century
thought that time was the same for everyone everywhere.
Our modern conception of time is based on Einstein's theory of relativity,
in which rates of time run differently depending on relative motion, and
space and time are merged
In the space time, where we live on a world line rather than a timeline.
Thus time is part of a coordinate, in this view.
Physicists believe the entire Universe and therefore time itself began
about 13.8 billion years ago in the big bang; see.
Whether it will ever come to an end is an open question.

24. Why we need time measurement
when 'Christian Huygens' (Dutch
scientist) made the Pendulum clock.
However, its invention goes as far back
as 1582and is credited to GalileoGalilei
Industrial Revolution: Without
accurate, globalized time, commerce
and travel could have faced some
serious issues and the industrial
revolution may not have taken place.

25. C LO C K S A N D C A LE N DA R S
Su n C l o c k
14 0 0 B . C
W a t e r
Cl o c k
13 0 0 B . C
E l e c t r i c
Cl o c k
18 9 5
A t o m i c
Cl o c k
19 4 9
M e c h a n i c a l
Cl o c k
12 8 3
P e n d u l u m
Cl o c k
16 5 6

26. C A LE N DA R S
Lu n a r
Ca l e n d a r
c . 3 0 0 0 B . C
Ci v i l
Ca l e n d a r
2 5 0 0 B . C
Gr e g o r i a n
Ca l e n d a r
15 8 2
J u l i a n
Ca l e n d a r
4 500 B .
C

27. Refrences
• http://www.cs.xu.edu/math/math125/09m/08EBJ.pdfHistory of Chronometry in Ancient Egypt
• http://science.howstuffworks.com/innovation/inventions/5-amazing-ancient- egyptian-
inventions4.htm http://www.egyptchronology.com/uploads/2/6/9/4/26943741/ch_3_investigati
ng_ancient_egyptian_calendars.pdf
• http://www.touregypt.net/egypt-info/magazine-mag03012001-magf1.htm
https://www.scribd.com/doc/56781350/Ancient-Egyptian-Chronology-Edited- by-Erik-Hornung-
Rolf-Krauss-And-David-a-Warburton
• http://www.time-for-time.com/clocks.htm http://www.historyofwatch.com/clock-history/clock-
timeline/ https://www.slideshare.net/bfrys/evolution-of-the-clock
https://www.scientificamerican.com/article/a-chronicle-of-timekeeping-2006- 02/

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