. Carnegie Institution of Washington publication. DESCRIPTION OF APPARATUS AND METHODS. 21 This is the largest spectrometer }et set up for emission and absorp- tion work. Greater sensitiveness of the radiometer would be necessary in order to be able to use a spectrometer of greater dimensions. THE RADIOMETER. The construction of the radiometer is shown in fig. 3, which is a section of the instrument at right angles to the one facing the spectro- meter. It was built according to the design of Nichols.^ The outer ^Topump ^^^^ ^^ ^ block of bronze, 5 by 5 by 10 cm., with an axial boring 3 cm. in
. Carnegie Institution of Washington publication. DESCRIPTION OF APPARATUS AND METHODS. 21 This is the largest spectrometer }et set up for emission and absorp- tion work. Greater sensitiveness of the radiometer would be necessary in order to be able to use a spectrometer of greater dimensions. THE RADIOMETER. The construction of the radiometer is shown in fig. 3, which is a section of the instrument at right angles to the one facing the spectro- meter. It was built according to the design of Nichols.^ The outer ^Topump ^^^^ ^^ ^ block of bronze, 5 by 5 by 10 cm., with an axial boring 3 cm. in diameter. The top was made from the neck of a large round bottle, into which was fitted a glass tube, which led to the exhaust pump. In series with the radiometer and pump was placed a tube containing gold foil on cotton to absorb the mercury vapor, which was found to electrify the vanes and thus cause one of them to adhere to the window. As a further precaution against electrification, the inner rock-salt window was partly cov- ered with tinfoil, which was in contact with the outer case. (See Appendix III.) There were two lateral borings in the outer case; the one in front of the vanes was 2 cm. in diameter and admitted the energy to be measured upon the exposed vane; the one in front of the mirror, not shown in the figure, was long and narrow and was used to read the deflections of the Th im. ,^- R, r (i77Z. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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