Hydrographical surveying : a description of means and methods employed in constructing marine charts (1920)
Wharton, W. J. L. (William James Lloyd), 1843-1905, Field, Arthur Mostyn, 1855- · London : J. Murray · leaf 483
t. As a very small amount of air leaking into the tubing willlargely affect the vacuum, and, consequently, the height of themercury column, two precautions are necessary, viz.— 454 HYDROGRAPHICAL SURVEYING [chap. xx. (a) Prevent leakage as much as possible by painting over allconnections with… … Fig. 108. (6) Connect a closed copper cj^linder to the highest portionof the system to act as an air trap, and fill it withwater. Any air that leaks into the system rises intothe cyUnder, displacing a certain amount of water,but not affecting the reading of the gauge. A gauge-glass fixed outside…
Hydrographic surveying · Nautical charts
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