. A new thermo-electric fluid-meter and hot-wire anemometer. apolated to higher temperaturesthan 1200° C«, it gives lower than the correctvalue of temperatures. As an example, the meltingpoint of platinum is found to be 1710° C» by thisequation, instead of 1750° C. or higher, as given byrecent work. 142 The Holman •qustion expreBsea the relationbetween E and t in the form B « mt*^(2) log Ban log t+log m and baa been found to be sufficiently^ acourate fornearly all ptirposes. Resulte obtained by the use ofthis equation agree with those obtained by the use ofequation (1) within approximately S°
. A new thermo-electric fluid-meter and hot-wire anemometer. apolated to higher temperaturesthan 1200° C«, it gives lower than the correctvalue of temperatures. As an example, the meltingpoint of platinum is found to be 1710° C» by thisequation, instead of 1750° C. or higher, as given byrecent work. 142 The Holman •qustion expreBsea the relationbetween E and t in the form B « mt*^(2) log Ban log t+log m and baa been found to be sufficiently^ acourate fornearly all ptirposes. Resulte obtained by the use ofthis equation agree with those obtained by the use ofequation (1) within approximately S° C» In the rangeof teraperaturea from 300° to 1200° C» When extra-polated above 1200° C, this equation (2) givesvalues of teinperatures more exactly than does equation(1), For high preolslon over very great teirperatureranges the use of more complicated formulas becomesnecessary. 4t4c)tta»*3»:**«4i4E>ti*«)t(43*:«>lf*>|ctc4[]4c4c /i/^£fl^0fl^£7-£A SEVrSAL iCtf. £^.A/f/r ~ 7~eMP£jf/\ru/(s Cuftv^^s /V-/V. 7~/ve/iAitac9v^ce<s. *fi*;:§ /oo eoosoo foo SOO ^00° /oo soo sec /ooo //eo /200 /^co/voc/^vo /too/700 //ss 144 COLD JUNCTION: As prerlously stated, the ooldJttnotlon is the joint where the free ends of thetwo metals of wbioh the thermocouple is composed,are connected to the leads running to the the reading of the meter is proportional tothe difference in temperature between the hot andoold Jiinctions, the temperature of the ooldJunction is an important consideration. To obtainaccurate meter readings, the oold Junction musteither be kept at a constant temperature or meansmust be provided for compensating for changes intemperature. To maintain a constant temperature,one method employed is to pack the cold Junction inice, a thermos bottle containing the ice, beingused for portable sets and some similar heat-con-taining device for permanent installations. Theice pack will last for about 24 hours, and it keepsthe cold junction at a cons
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