. Mechanical appliances, mechanical movements and novelties of construction; a complete work and a continuation, as a second volume, of the author's book entitled "Mechanical movements, powers and devices" ... including an explanatory chapter on the leading conceptions of perpetual motion existing during the past three centuries. 57. THERMOHYDROSCOPE. The instrument comprises es-sentially a double spiral, S, of zinc and iron and a prepared strand, H, of hair, extending from the end, a^ of thespiral, through an eye, r, over the roller,O, to the end of the index, Z. The eye,r, is carried by the
. Mechanical appliances, mechanical movements and novelties of construction; a complete work and a continuation, as a second volume, of the author's book entitled "Mechanical movements, powers and devices" ... including an explanatory chapter on the leading conceptions of perpetual motion existing during the past three centuries. 57. THERMOHYDROSCOPE. The instrument comprises es-sentially a double spiral, S, of zinc and iron and a prepared strand, H, of hair, extending from the end, a^ of thespiral, through an eye, r, over the roller,O, to the end of the index, Z. The eye,r, is carried by the spring,/, and is raisedor lowered by means of the set-screw, the eye be lowered, the strand of hairis subjected to tension, and the index, Z,thereby raised. If the eye be raised, thestrand of hair is slackened, and the in-dex falls by its own weight. In thismanner the index of the instrument isadjusted. The spiral, S, operates in the same manner as the spiral of a ther-. 44 MEASUREMENT OF POWER, SPRINGS. mometer. When the temperature rises the spiral curves inwardly, sothat its free end, a, moves downwardly to a. The tension of thestrand, H, is thereby diminished, and the index falls. Since the rel-ative moisture has remained the same, the length of the strand is notchanged. While the polymeter points constantly to fifty per cent., thethermohygroscope, through the falling of its index, shows that thetemperature has raised, and with a uniform temperature, a change ofthe index indicates change of the relative moisture. POWER OF SPRINGS. Reference to letters of formula :P. Maximum in Breadth of spring in Thickness of spring in Length of spring in Deflection of spring in inches. R. Radius of helical springs or points at which load is = max. 100,000 lbs. per sq. in. for elliptical springs, ) ^ , helical Brass. = 60,000 = 14,500E = modulus of elasticity. = 31,500,000 lbs. per sq. in. (steel).= 15,00
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