An ordinary weathercock provided with datum points may, in the majority of cases, suffice for the observation of the wind during the day; but recourse has to be had to different means to obtain an automatic transmission of the indications of the vane to the inside of a building. The different systems employed for such a purpose consist of gearings, or are accompanied by a friction that notably diminishes the sensitiveness of the apparatus, especially when the rod has to traverse several stories. Mr. Emile Richard, inspector of the Versailles waterworks, has just devised an ingenious system which, while considerably reducing the weight of the movable part, allows the weathercock to preserve all its sensitiveness. This apparatus consists of two principal parts--one fixed and the other movable. The stationary part is designated in the accompanying figure by the letters A and B and by cross-hatchings. This forms the rod or support. An iron tube, T, with clamps, P, at its lower extremity forms the base of the apparatus, and is hidden, after the mounting of the apparatus, by the ornamental zinc covering, Z. The upper part of the tube carries a shoulder-piece, upon which rests a bronze platform, E, and which is slightly inclined outwardly to prevent the accumulation of water on it.
Over the platform there move three crystal balls, which are held and guided by a horizontal disk movable around the stationary tube.
The movable portion, designed to receive the action of the wind and to indicate its direction, is designated by the letters C D and coarse lines. It consists of (1) a zinc tube, K, provided at intervals with copper rings, and entering the rod, A B, which serves as a guide for it; (2) of a bronze disk covered by an external ornament, O, fixed to the tube and resting on the balls; (3) of the vane, G, properly so called; and (4) of the cap, C, provided with bayonet catch, crowning the tube and covering the point of attachment of the wire of transmission. This latter consists of a simple brass or galvanized iron wire, f f, perfectly taut, and made fast in the top of the tube. After traversing as many stories as necessary this wire terminates, in the interior of the room where the observations are made, in a copper rod to which is fastened a horizontal arrow, F. The wire traverses the floorings through small zinc tubes; and, in the rooms through which it passes, it is protected by iron tubes. To the ceiling of the observing room there is affixed a wind-rose, R, on which the arrow reproduces all the motions of the vane.
This apparatus is now in operation in the different stations that the Versailles waterworks has established near the reservoirs of the plateau of Trappes, and it is also installed in several primary normal schools, where it is giving very good results.--La Nature.