A double-reflexion level
D S Perfect; D S Perfect; Optics Department, The National Physical Laboratory
Журнал:
Transactions of the Optical Society
Дата:
1929-01-01
Аннотация:
The level described in this paper was designed to assist the initial levelling of a floating system and to enable observations to be made on the constancy of level over extended periods of time. Its error may be determined by direct measurement and without reversal. The level in any direction is shown. The device has proved quite convenient in use and may possibly be found suitable for other purposes.
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