After transmitted sound the next thing is the visible signal, and this has been employed by human beings from the earliest ages in transmitting information to a distance. It is a method which will perhaps never be wholly abandoned. Observe the surveyors running a trial line. Far off is the chain bearer and here is the theodolite. The man with the standard watches for the signal of the man with the instrument. The language is _seen_ and the message understood, though no word is spoken. Here the sunlight is the wire, and the visible motion of the hands and arms the letters and words of the message.
The ancients were great users of this method. They employed it in both peace and war. They occupied heights and showed signals at great distances. The better vision of those days made it possible to catch a signal, though far off, and to transmit it to some other station, likewise far away. In this manner bright objects were waved by day and torches by night. In times of invasion such a method of spreading information has been used down to the present age. Nor may we fail to note the improved apparatus for this kind of signaling now employed in military operations. The soldiers on our frontiers in Arizona, New Mexico, and through the mountainous regions further north, are able to signal with a true telegraphic language to stations nearly a hundred miles away.
Considerable progress was made in telegraphy in the after part of the eighteenth century. This progress related to the transmission of visible messages through the air. In the time of the French Revolution such contrivance occupied the attention of military commanders and of governing powers. A certain noted engineer named Chappe invented at this epoch a telegraph that might be properly called successful. Chappe was the son of the distinguished French astronomer, Jean Chappe d'Auteroche, who died at San Lucar, California, in 1769. This elder Chappe had previously made a journey into Siberia, and had seen from that station the transit of Venus in 1761. Hoping to observe the recurring transit, eight years afterward, he went to the coast of our then almost unknown California, but died there as stated above.
The younger Chappe, being anxious to serve the Revolution, invented his telegraph; but in doing so he subjected himself to the suspicions of the more ignorant, and on one notable occasion was brought into a strait place--both he and his invention. The story of this affair is given by Carlyle in the second volume of his "French Revolution." One knows not whether to smile or weep over the graphic account which the crabbed philosopher gives of Chappe and his work in the following extract: