Some characteristics of the Marvin pyrheliometer . mostated bridge described in detailby This dial bridge reads directly to ohm, and by interpo-lating the readings of the galvanometer, the sensibility of which 5 Waidner and Burgess, this Bulletin, 8, p. 167; 1907 (Scientific Paper No. 55). 6 This Bulletin, 9, p. ; 1913 (Scientific Paper No. 202). 7 This Bulletin, 13, p. 547; 1916 (Scientific Paper No. 288). Foote) The Marvin Pyrheliometer 611 was determined at all points of the scale used, at least one morefigure in the resistance measurement could be relied upon. Thescale
Some characteristics of the Marvin pyrheliometer . mostated bridge described in detailby This dial bridge reads directly to ohm, and by interpo-lating the readings of the galvanometer, the sensibility of which 5 Waidner and Burgess, this Bulletin, 8, p. 167; 1907 (Scientific Paper No. 55). 6 This Bulletin, 9, p. ; 1913 (Scientific Paper No. 202). 7 This Bulletin, 13, p. 547; 1916 (Scientific Paper No. 288). Foote) The Marvin Pyrheliometer 611 was determined at all points of the scale used, at least one morefigure in the resistance measurement could be relied upon. Thescale deflections were always maintained as nearly zero as small measuring current passing through the thermometercoil in general had an appreciable heating effect. The current wasmaintained constant by using rather high voltage and externalresistance so that the small variations in resistance of the ther-mometer were negligible in their effect upon the magnitude of thecurrent. When necessary, the current was measured by the pyrheliometer. potentiometer3 pole double throw switch Fig. 2.—Wiring diagram jor obtaining observations during both heating and cooling of an electrical calibration Magnitude of heating and measuring current controlled by rheostats C and D. Galvanometer G criti-cally damped and maintained at the same sensibility during heating and cooling by rheostats Aand B. potentiometer method and controlled by an adjustable low-resistance slide wire. The constant current was allowed to flow dur-ing the entire radiometric calibration, during both heating andcooling of the receiver, so that it produced no net effect upon themeasurements. Fig. i shows the experimental arrangement for aradiometric calibration. The main difficulty with the electrical calibration was to de-vise a suitable means for measuring the resistance during theperiod of heating. The wiring diagram is given in Fig. 2. Themaximum current required for heating was small enough to permitthe use of
Size: 1946px × 1283px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectmeteorology, bookyear
