In one of the styles (Fig. 1) a spring, R, is attached at T to a fixed metallic rod, and presses against the rod, T¹. The current enters through the terminal, B, traverses the bobbins, passes through T, through the spring, through T¹, and makes its exit through the other terminal. The armature is attracted, and the point, P, fixed thereto draws back the spring from the rod, T¹, and interrupts the current; but, at the moment at which the point touches the spring, and before the latter has been detached from the rod, T¹, the electro-magnet becomes included in a short circuit, and the line current, instead of passing through the bobbins for a very short time, passes through the wire, T, the armature, and the rod, T¹, so that the extra current is no longer sent into the line. [Illustration: FIG. 1.] In another style (Fig. 2) the current is not interrupted at all, but enters through the terminal, B, traverses the bobbins, and goes through C to the terminal, B. [Illustration: Fig. 2.] As soon as the armature is attracted, the spring, R, which is fixed to it presses against the fixed metallic rod, T, and thus gives the electricity a shorter travel than it would take by preference. The current ceases, then, to pass through the bobbins, demagnetization occurs, and the spring that holds the armature separates anew. The current now passes for a second time into the bobbins and produces a new action, and so on. There is no longer, then, any interruption of the current, and the motions of the hammer are brought about by the change in direction of the current, which alternately traverses and leaves the bobbins. In a communication that he has addressed to us on the subject of these bells, Mr. Lippens adds a few details in regard to the mode of applying the ground pile to micro-telephone stations. Being given any two stations, he puts into the ground at the first a copper plate, and at the second a zinc one, and connects the two by a line wire provided with two vibrating bells and two telephone apparatus. The earth current suffices to actuate the bells, but, in order to effect a call, the inventor is obliged to run them continuously and to interrupt them at the moment at which he wishes to communicate. The correspondent is then notified through the cessation of noise in the bells, and the two call-apparatus are thrown out of the circuit by the play of the commutator, and are replaced by the micro-telephone apparatus. It is certainly impracticable to allow vibrating bells to ring continuously in this manner. The ground pile would, at the most, be only admissible in cases where the call, having to be made from only one of the stations, might be effected by a closing of the circuit.--_La Lumiere Electrique_. * * * * *