. The London, Edinburgh and Dublin philosophical magazine and journal of science . meter was not avail-able for this comparison, but inasmuch as it was only cali-brated to 0o,5 F., and was given but little weight in the finalresults, its effect on the values of the mechanical equivalentis entirely negligible. The stems of the thermometers are graduated in millimetres. Thermometer. Range. 1° C. occupies about Baudin 6163 , ,,6165 ,6166 -6°C. to40°°C. to33°° C. to 31° C. 9-0 „12-9 „ Platinum Thermometer.—The platinum thermometer usedin these experiments, and shown in fig. 1, was
. The London, Edinburgh and Dublin philosophical magazine and journal of science . meter was not avail-able for this comparison, but inasmuch as it was only cali-brated to 0o,5 F., and was given but little weight in the finalresults, its effect on the values of the mechanical equivalentis entirely negligible. The stems of the thermometers are graduated in millimetres. Thermometer. Range. 1° C. occupies about Baudin 6163 , ,,6165 ,6166 -6°C. to40°°C. to33°° C. to 31° C. 9-0 „12-9 „ Platinum Thermometer.—The platinum thermometer usedin these experiments, and shown in fig. 1, was constructed by Comparisons of Mercury and Platinum Thermometers. 7 the Cambridge Scientific Instrument Co., under the super-vision of Mr. E. H. Griffiths. It consists of a coil of fineplatinum wire wound on a mica frame whose edges areserrated, to receive the windings. The thick leads runningdown to this coil are held apart by mica washers, and thewhole thermometer is enclosed in a thin glass tube. Thethick leads are connected with the terminals marked P P. Fig. This thermometer was also provided with compensating leads,so that its indications are independent of the depth of stem-immersion, provided this immersion is sufficient to preventconduction from the outside along the leads to the coil. Thecompensating leads C C are simply a loop (not connectedwith the platinum coil) running down the stern parallel to themain leads P P throughout their length, so that they are 8 Messrs. C. W. Waidner and F. Mallory on exposed to the same temperature changes. These compen-sating leads are adjusted so that their resistance is equal tothat of the main leads P P. Now, obviously, if these leadsC C are placed in the other arm of the Wheatstone-bridge,as shown in fig. 2 below, they will exactly compensate forthe change in resistance of the leads to the coil, and conse-quently the resistance we measure, and hence the temperature,is independent of the depth of the immersion of th
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
