HISTORY AND PROGRESS.. 179 



iron, which serves as armature for the poles of an electro- 

 magnet. 



Bakeivell's Copying Telegraph. This is, properly speaking, 

 only a better mechanical construction of Bain's electro- 

 chemical telegraph. 



A clockwork is supported between the plates M, M' (Fig. 

 94), which puts the cylinder c in motion simultaneously with 



Fig. 94. 



the screw s, of the same length as the cylinder, and carrying 

 a nut, q, with style and connection, r. 



When the cylinder is turned by the clockwork, therefore, 

 the style travels up or down the cylinder according to the 

 direction of rotation of the latter, thereby marking a spiral 

 line whose convolutions are close together. 



Bake well used an electro-magnetic governor to attain 

 synchronism in the movements of the two apparatus, with- 

 out which it would certainly have been impossible to have 

 obtained any dependable results. 



100. Pouget-Maisonneuves, a native of France, writing in 

 the Comptes Rendues in 1856, describes a method of electro- 



N 2 



