Some studies made of the telegraph service of the Railway Company of the East (France) have resulted in a happy modification of the Callaud pile, rendering it easier of maintenance and reducing the consumption of the materials employed. As well known, the Callaud pile, which is exclusively employed for telegraphic purposes by certain railroad companies, consists of a glass vessel, of a circular piece of zinc suspended by hooks from the upper part of the vessel, and of a strip of copper resting on the bottom of the latter. This copper strip is riveted to a rod of the same metal which constitutes the positive electrode. In the bottom of the vessel there is placed a saturated solution of sulphate of copper, so that its level reaches to within a short distance of the lower part of the zinc, and the vessel is then filled with pure water. The zinc being attacked, there is formed a zinc sulphate, which always remains at the upper part of the vessel by reason of the difference in density of the solutions of sulphate of zinc and sulphate of copper, and the reduced copper deposits upon the strip in the center. It has been found necessary to cover the copper rod with a sheath of gutta-percha in order to keep it from being cut at the line of intersection of the two liquids, and this is the first inconvenience of the system. It is necessary, moreover, to keep the solution of copper at a certain degree of concentration by placing in the bottom of the vessel a supply of crystals of sulphate of copper. Hence it happens that the solution, being increased, eventually reaches the zinc, and the latter is thereupon attacked to no purpose, with a pure loss of copper through reduction. This is a second inconvenience, which can be remedied by introducing into the pile only a simply saturated solution without excess of crystals. It will be seen that, in this latter case, it is necessary to visit the pile quite frequently, to empty it by means of siphons, and to confide its maintenance to experienced persons only. This is why, up to the present, railroad companies have preferred the Daniell to the Callaud pile for alarm bells that control signal disks, despite the serious advantages of the Callaud pile and the inconvenience of the porous vessel that enters into the composition of the other. [Illustration: NEW SULPHATE OF COPPER PILE.] The modified Callaud pile is exempt from the defects that we have just pointed out. It differs from the old form in the substitution of a leaden tube, open at its extremities and dipping into the liquid of the pile, for the piece of copper or positive electrode. The lead, which is not attacked, and may serve indefinitely, is held in a vertical position by means of a foot made by cutting slits with a pair of scissors in the bottom of the tube, and bending back the strips thus formed. This foot also serves to prevent the tube from touching the zinc, by holding it in equilibrium.