146 ANNUAL OF SCIENTIFIC DISCOVERY. 



TELEGEAPHIC COMMUTATOR. 



M. Gamier, at the Great Exhibition of Paris, exhibited a telegraph " com- 

 mutator" of very ingenious construction, intended to be used with Morse's 

 telegraph. Instead of operating the key by hand for sending messages in the 

 common way, the message was composed beforehand, and disposed helically 

 along a cylinder, which is provided with two thousand keys, made of some 

 non-conducting substance, and according as they are arranged on the cylinder 

 they effect the breaking and closing of the circuit and write the message. The 

 operator turns a small winch, and his message is written a thousand miles dis- 

 tant in dots, dashes, and spaces, with the greatest rapidity. We witnessed a 

 dispatch of two hundred and ten words transmitted by this apparatus in one 

 minute. The mere idea thus ingeniously carried out by M. Gamier, as ap- 

 plied to the Morse telegraph, is undoubtedly new ; but it was substantially 

 applied to Bain's telegraph in 1847. Bain composed his messages on strips 

 of perforated dry paper, which opened and closed the circuit. These strips 

 were run between rollers by simply turning a small winch, and thus the mes- 

 sage was sent forward through the wires at a great rate. Scientific American. 



EXPERIMENTAL OBSERVATIONS ON AN ELECTRIC CABLE. 



In the Physical Section of the British Association, Glasgow meeting, Mr. 

 W. Whitehouse introduced the subject of submarine telegraphing. He re- 

 garded it as an established fact that the nautical and engineering difficulties 

 which at first existed had been already overcome, and that the experience 

 gained in submerging the shorter lengths had enabled the projectors to pro- 

 vide for all contingencies affecting the greater. Mr. Whitehouse then drew 

 the attention of the section to a series of experimental observations which he 

 had recently made upon the Mediterranean and Newfoundland cables, before 

 they sailed for their respective destinations. These cables contained an ag- 

 gregate of 1,125 miles of insulated electric wire and the experiments were 

 conducted chiefly with reference to the problem of the practicability of es- 

 tablishing electric communications with India, Australia, and America. The 

 results of all the experiments were recorded by a steel style upon electro- 

 chemical paper by the action of the current itself, while the paper was at the 

 same time divided into seconds and fractional parts of a second by the use of 

 a pendulum. This mode of operating admits of great delicacy in the deter- 

 mination of the results, as the seconds can afterward be divided into hun- 

 dredths by the use of a "vernier," and the result read off with the same 

 facility as a barometric observation. Enlarged fac-similes of the electric au- 

 tographs, as the author calls them, were exhibited as diagrams, and the actual 

 slips of electro-chemical paper were laid upon the table. The well-known 

 effects of induction upon the current were accurately displayed ; and con- 

 trasted with these were other autographs showing the effect of forcibly 

 discharging the wire by giving it an adequate charge of the opposite electricity 

 in the mode proposed by the author. No less than 8 currents 4 positive 

 and 4 negative were in this way transmitted in a single second of time 



