Instruments and methods of radiometry III. The photoelectric cell and other selective radiometers

✍ Scribed by W.W. Coblentz

• Publisher: Elsevier Science
• Year: 1918
• Tongue: English
• Weight: 149 KB
• Volume: 186
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/s0016-0032(18)90230-9

✦ Synopsis

THE behavior of the Marvin Py~heliometer has been investigated in detail. The instrument was calibrated by two methods, one in which a known amount of electrical enet,gy was dissipated in the receiver, and ,the other in which a known amount of" radiation from a black body was allowed to fall upon the receiver in the same manner as when the pyrheliometer is employed for solar measurenaents. The calibration by the two methods agreed within the limits of experimental error. T~he various constants of ,the instrument were determined and it was found that the fundamental constant relating the amount of energy received wi,th the rise in temperature of the receiver is independent of the rate of energy supply, at least for an electrical calibration. This fact could not be deter~mined with certainty for a radiometric cali.bration, because the anaount of energy which can be sut)pled radiometrically from a black body is very small compared to the energy of the solar r~/diation. The Marvin pyrheliometer calibrated as above was compared by solar observations with the U. S. Weather Bureau Smithsonian standardized pyr.heliometer S. J. No. I, which had been calibrated by comparison with the Smithsonian primary standard water flow pyrheliometer. The Marvin instrument gave 2 per cent. lower values than the Smithsonian pyrheliometer. This difference is within the error, s of observation in the calibration of the Marvin Pyrheliometer by the methods employed above.

Jan. 23, 1918. INSTRUMENTS AND METHODS OF RADIOMETRY III. THE PHOTOELECTRIC CELL AND OTHER SELECTIVE RADIOMETERS. ~ By W. W. Coblentz.