604 



THE APPLICATIONS OF PHYSICAL FORCES. [BOOK v. 



message, the conducting or insulating parts, that is, according as it 

 touches the silver ground of the paper, or the inkmarks of the message. 

 As far as this goes, except the difference in the kind of motion, the 

 principle of transmission is the same as in the pantelegraph described 

 above. 



The receiving apparatus is composed of a cylinder which has a 



Fiu. 3y4.^Meyer's pauteiugraph. 



motion of rotation absolutely identical with that of the transmitting 

 cylinder. While one makes a complete turn, the other does also and 

 with the same uniform velocity. Now on the surface of the 

 receiving cylinder is .a raised helix which passes round the whole length, 

 a complete turn of which is precisely equal to the length of the circum- 

 ference of the transmitting cylinder. Now consider a sheet of paper 



