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.[34]) “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 10½ inches. As we can give the lines a length of 4¼ inches, it follows that in twenty minutes Caselli’s apparatus furnishes the facsimile of the writing or drawing traced on a metallized plate 4¼ inches broad by 10½ 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 will easily be seen that Caselli’s method is capable of many important uses besides the transmission of facsimiles of handwriting. For instance, by means of it a portrait of some person who is to be identified—whether fraudulent absconder, or escaped prisoner or lunatic, or wife who has eloped from her husband, or husband who has deserted his wife, or missing child, and so on—can be sent in a few minutes to a distant city where the missing person is likely to be. All that is necessary is that from a photograph or other portrait an artist employed for the purpose at the transmitting station should, in bold and heavy lines, sketch the lineaments of the missing person on one of the prepared sheets, as in Fig. 10. The portrait at the receiving station will appear as in Fig. 11, and if necessary an artist at this station can darken the lines or in other ways improve the picture without altering the likeness. [Illustration: FIG. 10. FIG. 11.] But now we must turn to the greatest marvel of all—the transmission of tones, tunes, and words by the electric wire.