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no precise information of his family. Disabled finally by hæmorrhage of the lungs and loss of voice, he disposed of all his instruments to Garnier's Institute, and died of consumption, January 14, 1874, at forty years of age.

Four years later, in 1878, the Physical Society of Frankfort erected an obelisk of red sandstone over his grave in Friedrichsdorf bearing upon it a medallion of the great inventor.

The description of Reis's telephone is divided naturally into two sections. Here, fully illustrated in Professor Thompson's book, we have ten forms of transmitter, all imitating the mechanism of the ear, and applying the vibrations of an artificial tympanum to vary or modulate a current of electricity, by varying the degree of contact at a loose joint in the circuit, one or both of the members at this point of contact having an elastic bearing. This is the essential principle and method, leaving out certain adjuncts, of the most approved modern transmitters. In the very first transmitter made by Reis, in 1860 or 1861, a little curved lever is attached by one end to the center of an elastic tympanum, while the other end makes varying contact with a delicate spring, regulated by an adjusting screw—the surfaces of contact being of platinum—and the lever and spring included in a telephonic circuit equipped with a galvanic battery and receiver.

Of the receivers four forms are given. The first receiver made by Reis consisted of a knitting-needle wound with a helix of silk-covered copper wire, one end of which knitting-needle was thrust into the bridge of a violin, which served as a sounding box. This instrument was given to Reis for the purpose by Herr Peter, the music-teacher of Gamier Institute, and it is now preserved with other relics in the museum of that institution. In the second form the helix was laid horizontally upon a sounding-box (a cigar-box), and the knitting-needle, passed through it without contact, was supported by a "bridge" at each end. The third form was the electro-magnetic which will be described in connection with Fig. 1. Of this class of receivers Reis himself writes, "Electro-magnetism affords the possibility of calling into life, at any given distance, vibrations similar to the vibrations that have been produced (in the transmitter), and in this way to give out again in one place tones (sounds) that have been produced in another place." In the fourth form of receiver Reis recurred to the "knitting needle," more elaborately arranged. This is shown in Fig. 2.

Among these instruments of Reis are two noteworthy types of transmitter and two of receiver. They all happen to be grouped in two very early illustrations, published in the proceedings of learned bodies, and therefore of the highest authenticity. The first of these is contained in the report by Wilhelm von Legat to the Austro-German Telegraph Verein in 1862, printed in the journal of that society, and reprinted verbatim in Dingler's "Polytechnisches Journal" for 1863. This is shown in Fig. 1.