In order to prevent a train passing a danger signal during a fog or snowstorm without being seen by the engineer, the Southern Railway Company of France have attached to the locomotive a steam whistle, which is controlled by the signal. The whistle is connected with an insulated metallic brush placed under the engine. Between the rails there is a projecting contact bar, faced with copper, which is swept by the brush when the train passes. This contact piece is connected with the positive pole of a voltaic battery, the negative pole of which is in communication with a commutator on the signal post, from which a wire leads to the ground. When the signal is "line clear" the passage of the brush over the fixed contact produces no result; but when the signal marks "danger," the commutator brings the negative pole of the battery in direct communication with the ground, and when the brush passes over the contact the completion of the electric current causes the whistle to be sounded, so as to alarm the driver.--_L'Ingen. Univ._ * * * * * FURNACE FOR THE MANUFACTURE OF SULPHIDE OF CARBON. Sulphide of carbon (CS_2) is prepared by passing the vapors of sulphur over charcoal heated to redness. In laboratories, charcoal and roll brimstone are employed so as to obtain as pure a product as possible; but sulphide of carbon having now become so important a commercial product, and being employed for so large a number of industrial purposes, it has been found more economical to substitute coke for charcoal and pyrites for brimstone. The Messrs. Labois, in their system of furnace represented herewith, have had in view the manufacture of this product under as economical conditions as possible, by coupling over two connected fireplaces the retort in which the pyrites is distilled, and that in which the reaction of the sulphur and carbon takes place. The pyrites is fed from the hopper, A, into a distributing box, B, furnished with a valve which is maneuvered by a lever. From thence it descends into the retort, G, where it is roasted by the heat of the fireplace, L. The sulphur converted into a state of vapor passes through the conduit, R, into the coke or charcoal retort, G', which is divided into two parts by the partition, _g g'_, of refractory clay, and heated by the fireplace, L'. [Illustration: LABOIS'S SULPHIDE OF CARBON FURNACE.] The conduit, R', leads the sulphide of carbon in a state of vapor to the condensing apparatus. The uncombined sulphur which is carried along is deposited in the first part of the retort by the arrangement of the partition, which permits of passage only below. The registers, V and V', permit of the introduction of the sulphur vapor and the exit of the sulphide of carbon being regulated. The apparatus is so easy of installation that it may be applied without much expense to pyrites furnaces already in operation.