. Barometers and the measurement of atmospheric pressure. A pamphlet of information respecting the theory and construction of barometers in general. Barometers; Meteorological instruments. 47 striiment itself acts as a plumb line and takes a vertical position witli sufficient accuracy. It is desirable, however, for convenience in set- ting the barometer, as well as to insure the permanent verticality of the instrument, to steady it in supports which are first adjusted, once for all, so that the barometer is accurately vertical, as deter- mined by a plumb line applied alternately at the front a
. Barometers and the measurement of atmospheric pressure. A pamphlet of information respecting the theory and construction of barometers in general. Barometers; Meteorological instruments. 47 striiment itself acts as a plumb line and takes a vertical position witli sufficient accuracy. It is desirable, however, for convenience in set- ting the barometer, as well as to insure the permanent verticality of the instrument, to steady it in supports which are first adjusted, once for all, so that the barometer is accurately vertical, as deter- mined by a plumb line applied alternately at the front and one side. 91. Improved haromefer box.—Tlie standard pattern of barometer box now in use by the Weather Bureau is shown in Figure 29. This box must be securely attached to the wall in a location afford- ing good light and not subject to sudden changes of temperature. In many cases it will first be necessary to fasten to the wall hard- wood strips, to which the top and bottom of the barometer box can be secured by screws passing through metal plates provided for this purpose. Place the screw for holding the top of the box in the center of the top strip and suspend the box thereon. When the box is set about vertical (as determined by a plumb line) secure it firmly at the bottom by a screw passing through the metal plate into the wooden strip. The hooks in the top of the barometer box will, upon examination, be found to be adjustable in their positions. Place them in their central positions and hang thereon the " station" and " extra " barometers. Next, find the positions at the bottom for attaching the ring-shaped guides, one of which is shown in Figure 30. These rings should be slipped over the lower end of the barometer, and placed about the mid height of the cylindrical part of the cistern. Mark the screw holes and fasten the rings to the back of the box. The barometer when at rest should hang freely within this ring, and may be adjusted to do so by the
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Keywords: ., bookcentury1900, bookpublisherwashingtonu, booksubjectbarometers
