314 Mechanical Notation of Machinery. 
peated, a slight loss was always experienced, the cause of 
which Mr. Hennell was unable to ascertain.— Ann. of Phil. 
MECHANICAL NOTATION OF MACHINERY. 
A paper was lately read before the Royal Society, On the 
expression of the parts of machinery by signs; by C. Babbage, 
Esq. F.R.S. of which the following is a notice. 
In contriving his calculating engine *, Mr. Babbage found 
great difficulty from not having any regular method, by which 
he could find, at an instant’s notice, the precise time at which 
any given piece began to move, and also the state of motion or 
rest, at the same instant, of all the other parts. He therefore 
devised a method of expressing all the motions of any machine, 
however complicated, by signs. This it is almost impossible 
to describe without figures; but the following statement of the 
information which may be derived, almost at a glance of the 
eye, from the paper on which the “ mechanical notation” of any 
machine is expressed, will serve to show the important pur- 
poses to which the method may be applied. 
1, The name of each part is written at length, and there 
are references from the name to all the drawings. 
2. The number of teeth on each wheel, pinion, rack, or 
sector, is seen. 
3. Any given part, a wheel for example, being named, it 
will be seen what immediately moves it, what drives the mover, 
and so on up to the origin of motion: and not only will the 
whole succession of movements be visible, but the manner in 
which they act; as, for instance, whether by being permanently 
connected, or in the manner of a pinion driving a wheel, or 
by stiff friction, or at intervals only. 
4. The angular velocity of each part will be seen. 
5. The comparative angular velocity, or the mean velocity. 
6. All parts which require adjustment will appear; and the 
order in which those adjustments should be made is pointed out. 
7. At any part of the cycle of the engine’s motion, it will be 
seen at a glance what parts are moving, what are at rest; and 
it will appear in what direction the motions of the moving 
parts take place, and whether their velocity is uniform or vari- 
able. It will also be seen whether any given bolt or click is 
locked or not. 
8. Any part being named, the entire succession of its mo- 
tions and intervals of rest is at once presented to the eye; and 
if the contemporary movements at any particular time be re- 
quired, they will be visible adjacent to it. 
Mr. Babbage gives, as specimens of his method, the mecha- 
nical notation of the common eight-day clock, and of the hy- 
draulic ram.—Ann. of Phil. 
Results 
