1839.] Telegraphic Signals by induced electricity. 727 



fact, that the exquisite delicacy of the impressions of the touch transcends, 

 in some respects, the evidence of all the other senses. The eye and 

 ear are liable to distraction by casual sounds or phenomena, while the 

 attentive touch knows no interruption. The eye must close momentarily 

 and thus lose the observance of many rapid phenomena. Dazzled by 

 too vivid lights, and confused by too constant watching, vision soon 

 ceases to be accurate, while the frequent repetition of similar sounds 

 either becomes absolute silence to the ear, or like the murmuring of 

 a rivulet or the humming of insects, gradually narcotizes the observer. 

 Let the experimentalist attempt to count but 200 rapid strokes of a 

 faint bell, and he will at once acknowledge the imperfections of any 

 acoustic method. 



Thus with copper conductors equal in diameter to the iron wires 

 I employed, signals by pulsation are proved, to be communicable by 

 the method above described, in less than any appreciable period of 

 time, to the distance of 154 miles. 



Besides the method of telegraphing by pulsations and other signals 

 recognized by touch alone, there is another of which I have made 

 extensive trial, and which is capable of affording still more accurate 

 and intelligible and equally rapid results. 



Without any knowledge of the experiments quoted by Steinheils — 

 many months indeed before the paper by that author was published 

 in England — I attempted, and with success, to effect the transmission of 

 signals by using time-keepers at each terminus, and causing the 

 pulsation to be felt as the hands simultaneously passed a certain 

 number or letter on the dial. 



In these experiments I first employed a pair of watches modified for 

 my use by that ingenious artist Mr. Grant, of this city. All the move- 

 ments were taken out but those connected with the second-hand, and 

 a long lever was so constructed as to check the balance-wheel at 

 pleasure during the recoil. Round the second-hand was placed a 

 card dial laid off with three concentric circles divided each into twenty 

 parts. Omitting vowels and superfluous letters, the alphabet was laid 

 down in each circle so that the hand would during each revolution 

 point to any letter three times ; the compartments were moreover 

 numbered on the same principle, so that each figure from one to 

 ten would be pointed to six times in a revolution. 



The hand is passing each compartment during three seconds. The 

 observer receives say two pulsations, and is thereby referred to the 

 second circle, and reads the letter or cypher, according as the signal 

 be for spelling or numbering. 



