Chapter 5 Measurement of Atmospheric Pressure

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clearance enough to rattle, allowing for expansion.(10) Inspecting the barometerAfter disassembly, cleaning, and reassembly of the barometer, check the outer tube for mercurydrops. Stand the barometer upside down and leave overnight to check for mercury leakage.If mercury leakage is found, readjust the screws.If there is no leakage, turn the barometer back to a vertical setting and inspect the degreeof vacuum. It can be judged by a metallic sound like a click when mercury comes in contactwith the top of the glass tube. When this sound is heard in the same way as beforedisassembly, the degree of vacuum is satisfactory.If two barometers are available, compare their index errors before cleaning. Comparethem again after cleaning to make sure that there is no change in the index error.21
Tools for practice(a)Adjusting screw(b)Screw undercover(c)Brasscylinder(d)ScrewWash-leather bagBoxwood(a) Hempthread(b)Tighteningwith a threadFigure 5.11Mercury cisternFigure 5.12 Boxwoodwith wash-leather bag(c)Turning theboxwood counterclockwise withthe threadFigure 5.13 Method of turningboxwood if the screw is stiff(b)Opening ofthe tubeBeaker(a)ScrewFigure 5.14 Pouringmercury into a beakerFigure 5.15 Glass cylinder22
Page 3: (4) Disassemble the mercury cistern
Page 6 and 7: while the barometer is set on the h
Page 10 and 11: CylindercaseVacuumDetectingelements
Page 12 and 13: ln P 0P1Rz gdz0 T Vwhere:T v is the
Page 14 and 15: approximately 0.1 hPa in the pressu
Page 16 and 17: arometers and the mercury barometer
Page 18 and 19: 5.6.2 Aneroid InstrumentsGenerally,
Page 20 and 21: (2) Pre-install adjustmentDo not ca
Page 22 and 23: the gasket with a pair of tweezers
Page 26 and 27: Three screwsBoxwoodStrainBrass meta

Chapter 5 Measurement of Atmospheric Pressure

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