6. Studies of the Thermal State of the Earth : The Seventh Paper: A Sea Bottom Thermogradmeter
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概要
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An apparatus for measuring the geothermal gradient in the sea bottom, or a sea bottom thermogradmeter, has been constructed. The apparatus consists of a probe containing two pairs of thermistors and a recorder set in a pressure tight and water proof steel container. Each of the pairs of the thermistors forms the two arms of an A.C. bridge. The other two arms of the bridge comprise a continuous potentiometer. Signals from the two A.C. bridges consisting of two pairs of thermistors and two potentiometers are separately amplified through amplifiers X and Y. As the potentiometers rotate coaxially at the same speed as the recording drum, the phase angle of the output signal of the amplifier changes 180° when the potentiometer passes its balancing position. Therefore, as far as the phase angle is concerned, the output signal can be represented logically. It is the same for the output signal of the other amplifier. The output signals of the amplifiers X and Y are fed to an "and" gate circuit. The output signals of the gate circuit trigger the relay, and the contact of the relay makes or breakes when the potentiometers pass through their balancing positions, which give marks on the facsimile paper on the drum. Two pairs of thermistors give the temperature differences between the bottom and the top, and between the bottom and the middle point of the probe. The temperature differences ranging from 0°～2℃ can be recorded on the paper with an accuracy of 0.001℃ for about 2.5 hours. Some preliminary experiments indicated that the apparatus will serve for determining the terrestrial heat flow through the sea bottom.|日本列島をとりかこむ海域において地殻熱流量の実測を行なう目的のため,船より吊り下げ海底地層に貫入せしめて,海底での地温勾配を測定記録する装置を試作した.サーミスタを用いた交流ブリッヂ決を用い,0°～2℃程度の温度差が,0.001℃の精度で自動記録されるもので,その概要は本文第5図の通りである.全装置は耐圧容器に収められる.浅海測定用には,測定器を船上に留め感熱部のみを海底に突差す方式を採用した.太平洋上での試験結果はおおむね良好で,今後は実測を行なう予定である.なお,本研究は,科学技術庁特別調整費,文部省科学研究費によつて行たわれた.
- 1961-08-25