cxcviii GENERAL SUMMARY OF SCIENTIFIC AND 



The past year has likewise witnessed the invention of a 

 considerable improvement in telegraphy. The remarkable 

 duplex apparatus of Stearns, with the aid of which messages 

 are sent both ways on one wire and at the same time, has 

 been vastly improved upon by Messrs. Thomas A. Edinson 

 and George B. Prescott, who have discovered processes and 

 invented apparatus by means of which two messages can be 

 sent in the same direction, and two others in the opposite 

 direction, simultaneously upon the same wire. This inven- 

 tion has been named the Quadruplex, and is in successful 

 operation between the New York and Boston offices of the 

 Western Union Telegraph Company, and is stated in its 

 annual report, just issued, to be satisfactorily performing an 

 amount of work upon one wire quite equal to the capacity 

 of four wires worked with the ordinary Morse apparatus. 

 One of the greatest recommendations of the invention resides 

 in the fact that it calls for no changes in existing apparatus; 

 the old Morse Key is used without the need of specially edu- 

 cated operators, and with no duplication, save as to parts 

 of machinery. 



The first named of these gentlemen has, however, quite 

 lately announced another discovery of unusual interest and 

 importance in connection with what is known as the auto- 

 matic or chemical telegraph, in which the signals are made 

 and recorded by causing the current to pass through paper, 

 the latter being saturated with a chemical substance, which 

 changes in color when the current acts. Mr. Edinson calls 

 his discovery the Electro-motograph, and has founded upon 

 it a practically new system of telegraphy. In the chemical 

 telegraph the markings are made on the chemically prepared 

 paper by passing currents of electricity through a stylus 

 resting on the paper, which passes over a metal drum. Mr. 

 Edinson noticed that with certain compositions motion was 

 produced in the lever holding the stylus, which was caused 

 apparently by the sudden diminution of the friction of the 

 paper. 



It was found that paper prepared with caustic potash 

 and a stylus tipped with tin gave the best results. 



The following account of an experimental trial will best 

 serve to indicate the nature of the phenomenon. The stylus 

 of the Electro-motograph in question was of tin, but held in 



