. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 144 WORZEL AND HARRISON [chap. 9 proportional to the correction for the horizontal accelerations of the instrument. It is averaged and converted into a shaft rotation which is continuously added to the measuring-screw position through a differential gear-box (see Fig. 7). The ratio of shaft rotation to accelerometer output is adjusted in the laboratory before each trip during tests on a wave-simulating machine. In these tests the meter is adjusted to give the same reading with the machine in motion as it does when still. T
. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 144 WORZEL AND HARRISON [chap. 9 proportional to the correction for the horizontal accelerations of the instrument. It is averaged and converted into a shaft rotation which is continuously added to the measuring-screw position through a differential gear-box (see Fig. 7). The ratio of shaft rotation to accelerometer output is adjusted in the laboratory before each trip during tests on a wave-simulating machine. In these tests the meter is adjusted to give the same reading with the machine in motion as it does when still. The meter itself is very stable as regards drift and other spurious changes of reading. The reading of meter #3 at the Marine Physical Laboratory, San Diego, changed by only mgal between 21 February and 21 December, 1959, during which period it was used on five separate surveys on four different ships. The reading method depends on the equation of motion of the beam (see \mm\ Spring tension adjustment. ) where ^ is the deflection of the beam and /, ^ and k are instrumental constants. This couple can also be equated to L{g + z + B-C), (0) where z is the vertical acceleration of the meter, B is the difference between the total acceleration acting on the meter and the vertical component ( the instantaneous Browne correction), and L is an instrumental constant. C is proportional to the spring tension set by the measuring screw and would be. 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 Hill, M. N. (Maurice Neville), 1919-. New York : Interscience Pub.
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