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.
[Illustration: RICHARD'S WEATHERCOCK.]
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_.
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