Here is the little presentation about History of gear. I have tried to fullfil the topic properly as far as I can.

1. History of Gear
Presented by-
Name ID (Sec)
Abir Tasrif Anto 111-23-2364 (E)
David Nandy 111-23-2285 (E)
SM Mohiuddin Shah 103-23-2162 (E)
Mostofa Shakil 111-23-2306 (C)

2. Gear
A gear or cogwheel is a rotating
machine part having cut teeth, or cogs,
which mesh with another toothed part in
order to transmit torque, in most cases
with teeth on the one gear of identical
shape, and often also with that shape
(or at least width) on the other gear.

3. Two or more gears working in tandem are
called a transmission and can produce a
mechanical advantage through a gear ratio
and thus may be considered a simple
machine. Geared devices can change the
speed, torque, and direction of a power
source. The most common situation is for a
gear to mesh with another gear.

4. A gear can also mesh with a non-rotating
toothed part, called a rack,
thereby producing translation instead
of rotation.
The gears in a
transmission are
analogous to the wheels in a crossed
belt pulley system. An advantage of
gears is that the teeth of a gear
prevent slipping.

5. History Of Gear
Gears were already in use in 350 B.C. (about
2,300 years ago. One of Greek philosopher
Aristotle's writings includes a description about a
gear.
A hundred years later that day,
a Hellenistic mathematician
Archimedes (287~212 B.C.)
drew this diagram of a hoist
that was driven with a set
of worm and worm wheel.

6. .

7. In Japan, as seen from the picture below, gears were in
use in the Edo period (1603~1867) as a power source
for flour milling in waterwheels. The gear was as large
as one meter in diameter, and zelkova and oak trees
were used as the material.

8. A developed waterwheel
later used in japan

9. Leonardo da Vinci
(The True Inventor of Gear)
An Italian mathematician, Leonardo da Vinci
(1451~1519) is credited with developing the idea of
the chain and cog in the 15th century. However, it
took nearly 400 years for the idea to become a
practical aspect of bicycle design. By the 1880s,
the chain drive was commonplace.
Leonardo da Vinci who can be described
as a true "Renaissance man," recorded in
notebooks numerous drawings. Following slides
shows a comparison between his idea and modern
gears.

12. Conclusion
Comments:
Without gear the modern Industries,
Vehicles and Machine are not imaginable.
However the idea is ancient that has been
developed through all these years and still
developing further.
Reference:
• http://www.efunda.com/designstandards%20/gears/gear
s_history.cfm
• http://www.exploratorium.edu/cycling/gears1.html
• http://en.wikipedia.org/wiki/Epicyclic_gearing etc.