WIND. Air put in motion by some physical cause, so as to become a current or stream. Winds are denominated ao Cording to the points from which they blow; see Courses. A variety of machines have been invented at different times for ascertaining the strength or velocity of the wind; the annexed cut represent one which possesses the advantages of snop:, city of construction, and of being in its indications. It is thus formed :—A square open frame of wood or iron, a be, am pportedby the shift d; two cross pieces are fixed at ef, carrying an horizontal axis, which is moved by the action of the wind upon four sails, is i i, fixed to one end of the axis, and disposed to be influenced by the wind in the usual this axis is also fixed a conical of wood, on the smaller end of which, se, is attached a line with a weight, 4 appended to it. The wind now acting upon the sails, causes the barrel to revolve, and the line to be wound round its superficial. To prevent any retrograde motion, a ratchet wheel o, is fixed to the base or larger end of the cone ss, having a clicker falling into its notches as it revolves. It is evident that the force of the weight will continually increase as the line advances towards the base of the cone, by the power being applied at a greater distance from the axis or fulcrum ; consequently the variable force of the wind may be readily ascertained, by fixing the line at the smallest end, and marking the barrel with spiral lines, as taken up by the coiling of the rope round its superficies ; placing, also, between the line so drawn, numerical signs to denote the force of the wind; which might be calculated with tolerable precision, according to the known principles of the lever. The diameter of the
hre of the cone should .be such, in oomparison with the smaller end, that the very strongest wind should have meareely sufficient power to bring it en to the end of it.
The different velocities, forces, and oorraspondingpopalar appellations of winds are given in the following table, derived from the experiments of the late cele brated engineer, John 8meaton ; and detailed in the Philosophical nousdiau To which may be added a still more remarkable instance of the impetuosity of a hurricane, as related by M. Roelion. The velocity of the wind, as observed by him, was no less than 109 miles an hour, or 159.88 feet per second; and its fbrce against a perpendicular plane of a foot square, was estimated at 68.46 pounds avoirdupois. Of the causes and theory of winds, many very able philosophers have treated largely ; as Des Cartes, Rolled; Baoen, De Luc, Halley, Prevost, Derham, Mee, Muschenbrueck, Dalton, and ethers. We bays not room to introduce even a short abstract of their several theories, but must refer the curious reader to their writings, and the various parts of the Philosophies, Trasuactions.