726 Experiments on the communication of [[Sept. 



Each pulsation is practically simultaneous with the breaking of 

 contact with the battery. To give a rude idea of the velocity of the 

 signal, the contact being broken by a clicking wheel, on a perfectly 

 calm morning, at a distance of but sixty yards, the pulsation was 

 invariably felt at a sensible interval before the click which preceded 

 it was heard. Thus sound travelling at the rate of 1090 feet in one 

 second=to 121 feet in one-ninth of a second, the electrical impulse passes 

 through a total circuit of twenty-two miles, in less than that practically 

 insignificant fraction of time. This however conveys but an erroneous 

 notion of the almost inconceivable velocity of the impulse. Professor 

 Wheatstone has proved that the electrical accumulation of the Leyden 

 phial is discharged and circulates through copper conductors, one 

 fifteenth of an inch in diameter, with greater velocity than the progress 

 of light through the planetary spaces, and in the rate at least of 288,000 

 miles in a second. Now the discharges of the Leyden bottle and those 

 of induced coil electricity are in the closest circumstances analogous to 

 each other. 



Of the pulsations thus transmitted, it is perfectly easy to count six 

 in one second — thus with a little practice any signal number can be 

 made from one to six in one second. 



Besides the simple repetition of the pulsations up to nine, beyond 

 which they become indistinct for each signal, there are at least two modes 

 of conveying other sensations by this apparatus. If the connexion 

 between the battery of the primary coil be made and broken by a 

 ratchet-wheel of brass and silver, and the wheel be turned pretty rapidly, 

 a sensation analogous to the ruffle of a drum is so distinct as to render 

 mistake impossible. A third set is obtained by interposing a flat file 

 in the battery circuit, and interrupting this by drawing one wire along 

 the surface of the file; here instead of the ruffle, the feeling is that of a 

 blunt saw drawn lightly across the palms of the observer's hands. 

 It is difficult to express in words the differences in these distinguishing 

 signals, but the practice of a quarter of an hour will make the observer 

 so familiar with them, that he can without the slightest difficulty carry 

 on a communication by numbering or spelling with his distant corres- 

 pondent. With a tithe of the practice of a pianist or harpist, the most 

 perfect sympathy is practicable between the signalists, and that as fast 

 as the signal can be spelt. In short, with but little less velocity than 

 the articulations of language or the writing of stenographic characters, 

 this silent, but thoroughly intelligible, and still most secret of all cor- 

 respondence can take place. 



It is almost unnecessarv for me to remind the reader of the admitted 



