ON SOME MARVELS IN TELEGRAPHY. 259 



travels in the long circuit through the recording pointer at 

 the receiving station ; and a mark is thus made correspond- 

 ing to the inked part of the transmitting sheet instead of the 

 blank part, as in the older plan. 



The following passage from Guillemin's "Application 

 of the Physical Forces" indicates the effectiveness of 

 Caselli's pantelegraph not only as respects the character of 

 the message it conveys, but as to rapidity of transmission. 

 (I alter the measures from the metric to our usual system of 

 notation.*) " Nothing is simpler than the writing of the 

 pantelegraph. The message when written is placed on the 

 surface of the transmitting cylinder. The clerk makes the 

 warning signals, and then sets the pendulum going. The 

 transmission of the message is accomplished automatically, 

 without the clerk having any work to do, and consequently 

 without [his] being obliged to acquire any special knowledge. 

 Since two despatches may be sent at the same time and 

 since shorthand may be used the rapidity of transmission 

 may be considerable." "The long pendulum of Caselli's 

 telegraph," says M. Quet, " generally performs about forty 

 oscillations a minute, and the styles trace forty broken lines, 

 separated from each other by less than the hundredth part 

 of an inch. In one minute the lines described by the style 

 have ranged over a breadth of more than half an inch, and 

 in twenty minutes of nearly io| inches. As we can give the 

 lines a length of 45 inches, it follows that in twenty minutes 

 Caselli's apparatus furnishes the facsimile of the writing or 

 drawing traced on a metallized plate 4.5 inches broad by 10^ 

 inches long. For clearness of reproduction, the original 

 writing must be very legible and in large characters." 

 " Since 1865 the line from Paris to Lyons and Marseilles has 

 been open to the public for the transmission of messages by 

 this truly marvellous system." 



* It seems to me a pity that in the English edition of this work the 

 usual measures have" not been substituted throughout The book is not 

 intended or indeed suitable for scientific readers, who alone are accus- 

 tomed to the metric system. Other readers do not care to have a little 

 sum in reduction to go through at each numerical statement. 



