What are the disadvantages of using a Mercury Barometer how does an aneroid barometer takes care of this
The major disadvantage is the cistern and the mercury it contains require frequent cleaning to maintain the instrument's accuracy.
The aneroid barometer is more durable and compact, and much easier to read. The only particular advantage of a mercury barometer is that it's a direct measurement -- there's no calibration involved. If you can measure the height of the column above the pool and you know the density of mercury, you have the pressure.
An aneroid barometer , invented by the French 19th century engineer and inventor Lucien Vidie, uses a small, flexible metal box called an aneroid cell. This aneroid capsule (cell) is made from an alloy of beryllium and copper. The evacuated capsule (or usually more capsules) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. A mercury barometer has a glass tube of at least 84 cm in height, closed at one end, with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature at the instrument will reduce the density of the mercury, the scale for reading the height of the mercury is adjusted to compensate for this effect.
The major disadvantage is the cistern and the mercury it contains require frequent cleaning to maintain the instrument's accuracy.
The aneroid barometer is more durable and compact, and much easier to read. The only particular advantage of a mercury barometer is that it's a direct measurement -- there's no calibration involved. If you can measure the height of the column above the pool and you know the density of mercury, you have the pressure.
An aneroid barometer , invented by the French 19th century engineer and inventor Lucien Vidie, uses a small, flexible metal box called an aneroid cell. This aneroid capsule (cell) is made from an alloy of beryllium and copper. The evacuated capsule (or usually more capsules) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. A mercury barometer has a glass tube of at least 84 cm in height, closed at one end, with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature at the instrument will reduce the density of the mercury, the scale for reading the height of the mercury is adjusted to compensate for this effect.
