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"Crank M raises and lowers the two pistons C and D. The valves allow only for air to be removed from chamber J with a cutoff valve at K. The mercury filled barometer L measures the pressure in J." —Quackenbos 1859

Double Barrel Air Pump

"Crank M raises and lowers the two pistons C and D. The valves allow only for air to be removed from…

"Measures atmospheric pressure. Pressure from the atmosphere compresses the mercury in the tray forcing the mercury accordingly into the graduated tube." —Quackenbos 1859

Barometer

"Measures atmospheric pressure. Pressure from the atmosphere compresses the mercury in the tray forcing…

"As the mercury rises and lowers in the barometer, the float F turns the index, I. Index I points to the correct reading on the graduated scale S." —Quackenbos 1859

Wheel Barometer

"As the mercury rises and lowers in the barometer, the float F turns the index, I. Index I points to…