. A new thermo-electric fluid-meter and hot-wire anemometer. n 219 indicate the true zero, which must be used inobtaining the balance of the cell, jiurthermore,any error in the thermo-junction circuit intro-duces but half the per cent of error in thepotential measured across the drop previously stated, this is due to the fact thatthe thermal e, m, f. of the junction circuit isproportional to the square of the current through thefilament, whereas the potential across the dropresistance is directly proportional to this standard thermo cell that is properly constructedand
. A new thermo-electric fluid-meter and hot-wire anemometer. n 219 indicate the true zero, which must be used inobtaining the balance of the cell, jiurthermore,any error in the thermo-junction circuit intro-duces but half the per cent of error in thepotential measured across the drop previously stated, this is due to the fact thatthe thermal e, m, f. of the junction circuit isproportional to the square of the current through thefilament, whereas the potential across the dropresistance is directly proportional to this standard thermo cell that is properly constructedand operated should remain constant to at least5 parts in 10,000. It is probable that in view ofthe possibilities of improvement, the constancy ofthese cells will be greatly TESTS; In curve sheet Ho, 10 the results of testson standard thermo cells are shown. These testscovered a period of 14 to 23 months and are repre-sentative of a considerable number of cells. Thetable on the follo7;lng page, gives results ofthese tests in tabular 221 TABLE g 0, 19. Maximimi Period Cell Original variation from orig. Ho, of covered by No. e. m. f. Parts in Parts tests ,000 in 10,000 Months 1 27 23 2 21 14 3 1,1294 16 15 4 20 16 5 14 14 *6 5 4 #6 14 11 7 14 12 *8 17 15 #8 9 7 *Before filament temperature was acoidently increasedto reddening point. #After filament has been broizght up to reddening point. 222 RESULTS OF TESTS; The curves for cells Nos. 6 and 8indicate the effect of increasing the filamenttemperature atove the reddening point. Aspreviously stated, this produces a permanentincrease in the filament resistance. It followsthat when the filament resistance is increased, theheater current must he decreased to obtain the newbalancing point C. See Curve Ho» 11, a?hisdecrease in current of cours
Size: 1340px × 1865px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidnewthermoele, bookyear1920
