114 ANNUAL OF SCIENTIFIC DISCOVERY. 



posed to apply to the Submarine Atlantic Telegraph, consists in having only 

 local currents, which at the moment they are closed develop an induction 

 current of great intensity that shoots through the entire line. For this pur- 

 pose a coil of coarse wire is wound in three thicknesses around a piece of 

 soft iron of less than an inch in diameter, and about ten inches in length. 

 The local current is made to pass through it. Another coil of fine wire 

 is wound around the first, and is connected with the cable and with the 

 ground. 



The manner of making the type-wheels start right is very simple. The 

 operator stops the type-wheel by depressing a small lever, which catches a 

 pin so placed on the wheel that when stopped blank is opposite the printing 

 roller. This lever is thrown up by the printing roller, so that all the care 

 the operator of the other station has to take is to begin by a blank. 



Teeth of a slanting shape are cut on the side of the type-wheel, and each 

 time the lever which carries the printing roller is raised, a projection on its 

 side enters between two teeth of the type-wheel, and makes it slide back- 

 ward or forward as the case may be. The faster letters are telegraphed the 

 more often this correction is made, and it proves so effective that the vibra- 

 ting springs doing the office of pendulums require to be set with only a very 

 small degree of accuracy ; in fact, one may beat fifty and the other fifty-one 

 without any inconvenience resulting from the difference. 



The number of cups per hundred miles requisite for working House's 

 Telegraph is two hundred ; Morse's requires fifty, and Hughes's only four to 

 work both ways. A good operator can transmit two hundred letters a 

 minute; but this is the limit of human skill, and not that of the power of 

 the instrument. An average writer can pen one hundred and fifty letters 

 per minute. Consequently, one may play on a key-board or telegraph thirty- 

 three per cent, faster than he can write. 



Hughes's instrument is moved by a weight of seventy-five pounds, de- 

 scending two and a half feet in fifteen. This Aveight is raised now and then 

 by pressing down a treadle. This winding up does not require the stopping 

 of the machine an intermediate spring being so arranged as to act during 

 the time the weight is raising. 



BONELLPS AUTOGRAPHIC TELEGRAPH. 



The autographic telegraph of M. Bonelli, the Sardinian director of tele- 

 graphs, is attracting considerable attention on the continent, and bids fair 

 to supersede many of the existing systems of telegraphic communication. 

 Indeed, the action of this telegraph is sufficiently wonderful, and its advan- 

 tages sufficiently obvious, to give it a claim to public interest. It reproduces 

 with the utmost exactitude any inscription or design which may be traced 

 upon the strip of metal ized or conducting paper, which is given to the 

 sender of a message ; and this it does with such rapidity, that four times the 

 number of words that can in any given time be transmitted by the usual sys- 

 tem, can, it is confidently asserted, be sent by this method. Many advan- 

 tages beside that of rapidity are, moreover, to be derived from an unerring 

 process of autographic reproduction. It is well known that the various sym- 

 bols or ciphers, by means of which secrecy is ensured in confidential and 

 important communications, are a constant source of error, owing to the 

 necessary ignorance of the clerk who transmits the message with regard to 

 the value and significance of the signs employed. In a copying telegraph, 



