. Carnegie Institution of Washington publication. ACOUSTICS AND GRAVITATION. n- IO~ = 32 fringes per turn of screw hs ' In the experiments fringes of one-half scale-part were installed. In sep- arate experiments, immediately after closing the cock C, a half turn of the screw produced a displacement of , , , , scale-parts; as the average, therefore, scale-parts per turn or about 33 fringes per turn. This agrees as closely as may be expected with the number computed. The pressure increment per turn of screw is dp = n\/2 cm. of mercury or per turn of screw
. Carnegie Institution of Washington publication. ACOUSTICS AND GRAVITATION. n- IO~ = 32 fringes per turn of screw hs ' In the experiments fringes of one-half scale-part were installed. In sep- arate experiments, immediately after closing the cock C, a half turn of the screw produced a displacement of , , , , scale-parts; as the average, therefore, scale-parts per turn or about 33 fringes per turn. This agrees as closely as may be expected with the number computed. The pressure increment per turn of screw is dp = n\/2 cm. of mercury or per turn of screw about io~3 cm.; per fringe, therefore, 3 X io~6 cm. of mercury •as anticipated. A range of about 2 or 3 turns of screw was possible with each fringe, , the range of pressure measurement should be from 3Xio~5 to 3 X io~3 cm. of mercury. Experiments of the same kind were made in great variety. There is no difficulty is using much larger fringes, so that 3 X icr6 cm. of mercury should be appreciable. By exhausting both sides of the U-tube the apparatus becomes a vacuum gage. I did not, however, attempt such work, as the present appara- tus was not well adapted for the purpose. \ . \ v "A. a _=_ • .^"^ • •• • C^/T~^ t» I. 4. Air-thermometer.—If the cock C is permanently closed, the air-space A becomes the bulb of an air-thermometer of approximately constant volume. In this way the heat produced by the rays of light L' may be measured. In a variety of experiments of the kind, the mean result was about 10 scale-parts or 20 fringes in a lapse of 210 seconds. If r denotes absolute temperature, the intrinsic equation may now be written which reduces as above to dp , = ' V~~= T dh dh^dr 76 ~'' Thus, if T = 300°, dr =rn — ( —7 H 7+ I = 2 \76 zHJ and for n=20 in 210 seconds, = ° Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrati
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