Chapter 5 Measurement of Atmospheric Pressure
Chapter 5 Measurement of Atmospheric Pressure
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 <strong>of</strong> 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 degree<strong>of</strong> vacuum. It can be judged by a metallic sound like a click when mercury comes in contactwith the top <strong>of</strong> the glass tube. When this sound is heard in the same way as beforedisassembly, the degree <strong>of</strong> 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