. The Encyclopaedia Britannica; ... A dictionary of arts, sciences and general literature. hed, a is a flat circularmetallic box, having its upper and under surfaces corrugatedin concentric circles. This box or chamber being partiallyeihausted of air, through the short tube 6, which is sub-sequently made air-tight by soldering, constitutes a spring,which is affected by every variation of pressure in theexternal atmosphere, the corrugations on its surface increas-ing its elasticity. At the centre of the upper surface ofthe exhausted chamber there is a solid cylindrical projectionX, to the top o
. The Encyclopaedia Britannica; ... A dictionary of arts, sciences and general literature. hed, a is a flat circularmetallic box, having its upper and under surfaces corrugatedin concentric circles. This box or chamber being partiallyeihausted of air, through the short tube 6, which is sub-sequently made air-tight by soldering, constitutes a spring,which is affected by every variation of pressure in theexternal atmosphere, the corrugations on its surface increas-ing its elasticity. At the centre of the upper surface ofthe exhausted chamber there is a solid cylindrical projectionX, to the top of which the principal lever cde is attached,as shown in the drawing. This lever rests partly on aspiral spring at d; it is also supported by two verticalpins, with perfect freedom of motion. The end e of thelever is attached to a second or small lever/, from whicha chain y extends to h, where it works on a drum attachedto the axis of the hand, connected with a hair spring at //,changing the motion from verticod to horizontal, andregulating the hand, the attachments of which are made to. Fia. S.—Aneroid Baromeier. the metallic plate i. The motion originates in the corru-gated elastic box a, the surface of which is depressed orelevated as the weight of the atmosphere is increased ordiminished, and this motion is communicated through thelevers to the axis of the hand at h. The spiral spring onwhich the lever rests at d is intended to compensate forthe effects of alterations of temperature. The actualmovement at the centre of the exhausted box, from whencethe indications emanate, is very slight, but by the actionof the levers this is multiplied 657 times at the point ofthe hand, so that a movement of the 220th part of an inchin the box carries the point of the hand through threeinches on the dial. The effect of this combination ia tomultiply the smallest degrees of atmospheric pressure, aoas to render them sensible on the index. The instrument requires, however, to be repeatedly
Size: 1586px × 1576px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidencyclopaedi, bookyear1902
