Telegraph wires are often, under the influence of the winds, submitted to vibrations which reproduce the phenomena of the Aeolian harp. The electric telegraph, which, before the construction of the Kehl bridge, directly traversed the Rhine, very frequently resounded, and the observer who placed his ear against the poles on the bank of the river was enabled to hear something like a far-off sound of bells.--_La Nature_. * * * * * PHYSICS WITHOUT APPARATUS. MANUFACTURE OF ILLUMINATING GAS. [Illustration: FIG. 1.--PRODUCTION OF ILLUMINATING GAS.] Burn a piece of paper of about the size of the hand upon a clean porcelain plate, and this will serve to show the phenomena of carbonization and the formation of empyreumatic products under the action of heat. Under the burned paper there will be found a yellowish deposit which sticks to the fingers, and which consists of oil of paper produced by distillation. An idea of the production of illuminating gas through the distillation of coal may be easily given by means a single clay pipe. Upon filling the bowl of this with fragments of coal, closing the opening with clay, and, after the latter is dry, placing the bowl in a coal fire so that the stem shall project, gas will soon be observed issuing from, the latter, and, when lighted, will give a very bright flame. If the pipe seems to be a little too costly, recourse maybe had to a large piece of wrapping paper rolled into the form of a cornucopia, and held in the left hand by means of the pointed end. If, after an aperture has been made in this near the point, the base be lighted, the heat developed by the flame will produce a sort of distillation of the organic matter of the paper, and the empyreumatic and gaseous products will rise in the cone, and make their exit through the orifice, where they may be lighted with a match (Fig. 1). It goes without saying that this experiment lasts but a few seconds; but, as short as this period is, it is sufficient to give a demonstration of the production of illuminating gas through the distillation of organic matters. Care should be taken not to set anything on fire while performing it, and it is well to operate over a pavement, and far from any inflammable materials. ELASTICITY OF BODIES. [Illustration: FIG. 2.--EXPERIMENT ON THE ELASTICITY OF BODIES.] Mould a piece of fresh bread with the fingers so as to give it the size and shape shown in Fig. 2. If this object be placed upon a wooden table, and a hard blow be given it with the fist, it will be found impossible to put it permanently out of shape. However hard be the blow, the elastic material, although flattened for an instant, will always resume its original form. If the object be thrown on the floor with all one's might, the result will be the same; its elasticity will always cause it to spring back to its original form. The experiment will only succeed when the bread that is used is very fresh and soft.