Page:Popular Science Monthly Volume 44.djvu/809

 evidence against the submergence is now almost, if not quite, conclusive.

In the brief outline now given of the facts of glacial geology-bearing upon the former existence, the thickness, extent, and motion of ice-sheets, it has only been possible to treat the subject very broadly, omitting all those details and minor difficulties which can not be discussed within the limits of a popular article. My object has been to explain the nature and amount of the converging evidence demonstrating the existence of enormous ice-sheets in the Northern hemisphere, to serve as a basis for the discussion of the glacial origin of lake-basins, which will form the subject of another article.—Fortnightly Review.



T is one hundred years ago (the 22d of March, 1793) since a young man named Claude Chappe presented himself at the bar of the Legislative Assembly. He carried there a secret vocabulary composed of nine thousand nine hundred and ninety-nine words, represented by some numbers, and destined to be transmitted by a system of visual telegraphy by means of a machine carrying the signals from station to station.

The examination of the machine was promptly confided to a committee, which reported in favor of its adoption, and a little after, the Convention voted the funds necessary to the establishment of a trial line.

It is this memorable event—the origin of the most marvelous discovery of our times—which the telegraphic people have recently fêted as solemnly as possible.

On this occasion it has appeared to us useful as well as interesting to retrace the history of telegraphy in France, to note briefly the successive stages and the perfecting of the telegraphs which have transformed the world.

Some essays in telegraphy were made in modern times, notably at the end of the seventeenth century, by Dr. Hooke, an English physician, who made service of an apparatus consisting of some characters of a sufficient size for being perceived at a distance, each one corresponding to a letter of the alphabet.

Under the reign of the fourteenth Bourbon clique, a savant (G. Amontons), who became later on member of the Academy of Sciences, took up the study of the problem of aërial telegraphy. Highly interesting was the result thereof. Fontenelle, the 