264 Mr. Babbage on a method of expressing 
Let us now enquire into the source of motion of the minute 
hand. On looking down to the space in which the origin of 
motion is given, we observe an arrow point, which conveys 
us to the 
Cannon pinion, with which it is connected permanently. 
The cannon pinion is driven by the centre or hour wheel, 
with which it is connected by stiff friction. 
The hour wheel is driven by its pinion, to which it is per- 
manently attached. 
The hour wheel pinion is driven by the great wheel, into 
which it works. 
The great wheel is driven by the fusee, with which it is 
connected by a ratchet. 
The fusee is driven by the spring barrel or main spring, 
which is the origin of all the movements. 
When that part of the notation which relates to the suc- 
cessive movements of the machine is of considerable extent, 
it is convenient to write on a separate piece of paper the 
names of every part, at the same distances from each other 
as the indicating lines, and exactly as they are placed at the 
top. By sliding this paper down the page to any part which 
is under consideration, the trouble of continual reference to 
the top of the drawing will be avoided. 
Plate X. represents the hydraulic ram ; its mechanical 
notation is added below it. 
A, is the supplying pipe. 
B, is the great valve. 
C, the valve into the air vessel. 
D, the air vessel. 
E, the ascending water. 
F a the small air valve : — its office is to supply a small 
