518 



Mechanical Notation. 



[Mat, 



6. At each transfer of movement the method by which it was accomplished 

 will become apparent, whether by wheel and pinion, by a stud, by stiff friction, 

 or by any other method. 



7. All the adjustments which are necessary in order to set the machine in 

 action will be pointed out, and the order in which they ought to be made will 

 be indicated. 



8. The whole course of action of every part will be visible in every stage of 

 the progress of the machine. If it be a wheel, the time and direction of its 

 motions will appear, and also the times at which it rests; if the part examined 

 be a bolt or click, the times at which it is bolted or locked, and those during 

 which it is in the reverse state, will be seen. These particulars will be discovered 

 by casting the eye down the vertical line belonging to each part, which was 

 named at the top of the drawing. 



1). On passing the eye along any of the horizontal lines dividing the cycle of 

 the engine's movements, every contemporaneous motion, as well as its direc- 

 tion at that precise time, becomes visible, as also the position of those parts 

 which are at rest. 



Mr. Babbage found much time was gained in the construction of his calcu- 

 lating engine by employing this mechanical notation; and to convey as accu- 

 rately as possible a knowledge of this very useful system, we subjoin the two 

 following examples. The first represents the action of Montgolfier's hydraulic 

 ram ; the second is a description of a double tumbler lock. The vertical lines 

 are denominated the lines of indication — a state of motion is denof"d by a 

 contin;i'jus stroke — a state of rest by a series of dots. When motion takes 

 place from left to right, the stroke is drawn on the left side of the indicating 

 line, and vice versa. 



In example 1. The first horizontal arrow connects the indicating line of g 

 and a, denoting that gravity acts upon the descending water. The second 

 horizontal arrow connects the indicating lines of a and b, shewing that the 

 descending water raises the great valve. The third arrow connects^ andb, shew- 

 ing that gravity then acts upon the great valve, and soon for the moving powers. 



'J'he cycle of the machine's action is described thus: Looking at the indi- 

 cating line of rt, the lower line shows that the descending water acts incessantly ; 

 its gradual reccsiou from the indicating line shows this motion to be gradually 

 accelerated; when arrived at its maximum it suddenly changes its direction, 

 as is shown by the curve crpssing the line of direction. During this period b, r, 

 and/ are at rest, a, d, e, g, and h are in continual action. But it is needless to 

 proceed with this ex()lanati()n, or with that of the second example. The prin- 

 ciple being once clearly laid down, the application will be manifest on inspection. 



10 > n totO ^ 



s rt V " a « M s 







