“The galvanic current coming from the battery (which I compose generally of three or four good elements) is introduced at the conducting screw near (_b_) wherefrom it proceeds to the quicksilver, the movable angle, the platina plate and the complementary telegraph to[29] the conducting screw (_s_). From here it goes through the conducter to the other station B and from there returns to the battery. “The apparatus B, a sonorous box on the cover of which is placed the wire-spiral with the steel axis, wich will be magnetic when the current goes through the spiral. A second little box is fixed on the first one, and laid down on the steel axis to increase the intensity of the reproduced sounds. On the small side of the lower box you will find the correspondent part of the complementary telegraph. “If a person sing at the station A, in the tube (_x_) the vibrations of air will pass into the box and move the membrane above; thereby the platina foot (_c_) of the movable angle will be lifted up and will thus open the stream at every condensation of air in the box. The stream will be re-established at every rarefaction. For this manner the steel axis at station B will be magnetic once for every full vibration; and as magnetism never enters nor leaves a metal without disturbing the equilibrium of the atoms, the steel-axis at station B must repeat the vibrations at station A and thus reproduce the sounds which caused them. “_Any_[30] sound will be reproduced, if strong enough to set the membrane in motion. “The little telegraph, which you will find on the side of the apparatus is very usefull and agreable for to give signals between both of the correspondents. At every opening of the stream and next following shutting the station A will hear a little clap produced by the attraction of the steel spring. Another little clap will be heard at station (B) in the wire-spiral. By multiplying the claps and producing them in different measures you will be able as well as I am to get understood by your correspondent. “I am to end, Sir, and I hope, that what I said will be sufficient to have a first try; afterward you will get on quite alone. “I am, Sir, “Your most obediant Servant, “Ph. Reis. “Friedrichsdorf, 13/7, 63.” [=9.=] REIS’S PROSPECTUS. [The following “Prospectus” of instructions was drawn up by Reis to accompany the Telephones which were sold by Herr Wilh. Albert of Frankfort. The author of this book is in possession of original copies, of which a number are extant. The “Prospectus” was also reprinted in its entirety at page 241 of Professor Pisko’s book ‘Die neueren Apparate der Akustik,’ published at Vienna in 1865.] TELEPHON.