Improvements in and relating to mercurial barometers

摘要

924,994. Mercury barometers. SCIENTIFIC INSTRUMENTS (GLASGOW) Ltd., and C. H. DREWELL. March 13, 1961 [March 16, 1960], No. 9228/60. Class 106 (2). The column of mercury in a mercury barometer is contained in a short upper closed glass tube 31 and a longer plastic tube 11 extending into a mercury chamber 15 having a fiducial point 16 and a piston 17 movable by screw 21 to adjust the mercury level, the tubes being supported centrally within an outer transparent plastic casing 10 by flanges 13, 14, 12 and a bush 29. A baffle-plate 28 deflects air bubbles into the annular space 30. Air trapped in the mercury chamber 15 can escape by way of leather plugs 24 and 18 through an outlet passage 25 and a passage formed by a flattened part 20 of a threaded stud 19 in the piston 17. The latter and the boss 29 make sealing contact with the tubes by means of 0-rings.