182 Description of an Electro-motive Engine. 



of a small wheel fixed upon its axle. This is managed by 

 means of the apparatus represented at Fig. III. A. is a steel 

 toothed wheel fixed on the axle of the fly wheel, Fig. II. 

 D. D. are brass cheeks moveable on the projecting sides of 

 the steel wheel, and screwed together at F. C. is a double 

 catch which freely allows the brass pieces D. D. to be thrown 

 back, but when drawn forward by the keeper, catches the 

 toothed wheel A., and thus causes the fly wheel to turn. E. is 

 the pin to which the bar from the keeper is attached ; it can be 

 shifted further from, or nearer to the main axle, at pleasure. 

 When the motion of the fly wheel is required to be reversed, 

 the brass pieces D. D. are turned under the main axle, the 

 catch being made to act in this position also, merely by push- 

 ing a spiral spring to the other side of it. 



The action of the engine is instantly arrested by placing 

 a thin slip of ivory between E. and C. D., and as quickly 

 restored by withdrawing it. It is unnecessary to say that no 

 impulse is required to renew the action. 



There being no change of poles in these magnets, I find 

 that a certain degree of permanent power is induced in the 

 large bar. This is no disadvantage ; on the contrary, it helps 

 to repel the keeper when the current is shifted to it. 



As the working power of the magnet is greatest when 

 nearest to the keeper, and as the strokes are also quicker in 

 this position, nothing is apparently gained by allowing the 

 latter to recede very far from the former. The manner in 

 which the power is applied to the fly wheel renders it un- 

 necessary, and in this respect the arrangement differs essenti- 

 ally from the crank. The adjustment of the bar R., where it 

 is attached to the keeper and fly wheel, as shown in Fig. II., 

 enables us to regulate the length of the stroke at pleasure. 



The model from which this description is taken consists of 

 two electro-magnets, side by side, as seen at Fig. IV. They 

 each act independently on the axle of the fly wheel, as already 

 described. Several may of course be so placed. I have placed 



