The London, Edinburgh and Dublin philosophical magazine and journal of science . uter water-bathwhich was heated by a gas-jet, the gas being automaticallycut off when the temperature rose to a given value, and beingallowed to come on again as soon as the temperature hadfallen below that value. In fig. 1, A B C are zinc vessels : A is the air-bath, con-taining the standard resting on cottonwool; B the surroundingwater-bath, closed at the top and containing the thermo-meter D ; C the enclosing jacket, between which and B thehot air from the gas-jet passes, heating the water-jacket onits way. D i
The London, Edinburgh and Dublin philosophical magazine and journal of science . uter water-bathwhich was heated by a gas-jet, the gas being automaticallycut off when the temperature rose to a given value, and beingallowed to come on again as soon as the temperature hadfallen below that value. In fig. 1, A B C are zinc vessels : A is the air-bath, con-taining the standard resting on cottonwool; B the surroundingwater-bath, closed at the top and containing the thermo-meter D ; C the enclosing jacket, between which and B thehot air from the gas-jet passes, heating the water-jacket onits way. D is an alcohol thermometer with a mercury-index F, which, on the expansion of the alcohol, is pushed upthe narrow tube L, and electrically connects the two platinumwires/i and/2» J *s the gas-jet for heating the water-bath ;K a baffle-plate over the gas-jet, to prevent the flame heating the Electromotive Force of Clark Cells with Temperature. 287 the water-bath directly. E is an escape-tube, which servesto carry off some of the heat of the jet ; G is a little by-pass, Fig-. burning at the mouth of the tube E, and serves to relightthe main jet when extinguished. M is an electromagnet ;H, its armature, is pivoted at S and weighted at P, and carriesa platinum wire Q which dips into the mercury cup Qf. When the temperature of the water-bath has reached acertain arbitrary value, the mercury-index electrically con-nects/! and/2, completing the circuit of the electromagnet Mand the battery Z. The electromagnet being thus excited,attracts its armature H, which compresses the indiarubbertube T that feeds the main gas-jet J, between the brasspiece N and the adjustable wooden block W, and so extin-guishes the light. The water-bath now cools slowly till itstemperature has fallen below the fixed value, and the contactis broken at/2 by the falling of the mercury-index. Whenthis happens, the armature of the electromagnet is releasedand pulled up at once by the weight P, the gas coming onag
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
