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according accurate adjusted Admiral allow amount aneroid arrangement ascertaining atmospheric pressure attached barometer becomes boiling bore bottom brass bulb carried cause changes cistern cold column consists constructed containing contraction correction cylinder described determined dial diameter difference direction divided effect elevation equal extremity fall feet fitted fixed float fluid frame gauge given gives glass graduated hand heat height Hence horizontal hygrometer important inches increase indications instrument length less limb liquid lower maximum means measuring mercury metal meteorological motion move necessary Negretti observation obtained ordinary pass placed plate portable portion position present principle quantity radiation rain range reading receive render represented rise round scale screw shows side spring stand standard sufficient supported surface Table taken temperature thermometer tube turned upper usually vapour vernier vertical weather wind Zambra zero
Sivu 84 - The refrigeration at night is extreme when the air is dry. The removal, for a single summer night, of the aqueous vapour from the atmosphere which covers England, would be attended by the destruction of every plant which a freezing temperature could kill. In Sahara, where 'the soil is fire and the wind is flame,' the cold at night is often painful to bear.
Sivu 11 - ... and then fall, it presages a change, though not to so great a degree as if it had stood lower : besides which, the direction, and force of wind, are not in any way noticed. It is not from the point at which the mercury may stand that we are alone to form a judgment of the state of the weather, but from its rising or falling ; and from the movements of immediately preceding days as well as hours, keeping in mind effects of change of direction, and dryness, or moisture, as well as alteration of...
Sivu 19 - ... much lower than the lowest pressure to which marine barometers are likely to be exposed ; and by compressing the air it can be made to read higher than the mercury ever stands at the level of the sea. The tube of the standard is contracted...
Sivu 26 - A rapid rise Indicates unsettled weather. A gradual rise indicates settled weather. A rise with dry air and cold increasing- in summer indicates wind from the northward; and if rain has fallen, better weather may be expected. A rise with moist air and a low temperature indicates wind and rain from the northward.
Sivu 85 - Shallow pits are dug, which are partially filled with straw, and on the straw flat pans containing water are exposed to the clear firmament. The water is a powerful radiant, and sends off its heat copiously into space. The heat thus lost cannot be supplied from the earth — this source being cut off by the non-conducting straw. Before sunrise a cake of ice is formed in each vessel.
Sivu 105 - ... passes into a vessel of water, placed at such a distance as to allow a length of conducting thread of about three inches. The cup or glass is placed on one side and a little beneath, so that the water within may not affect the reading of the dry butt) thermometer.
Sivu 53 - ... deteriorate in time, though slowly." " The aneroid is quick in showing the variation of atmospheric pressure ; and to the navigator who knows the difficulty, at times, of using barometers, this instrument is a great boon, for it can be placed anywhere, quite out of harm's way, and is not affected by the ship's motion, although faithfully giving indication of increased or diminished pressure of air.
Sivu 88 - Into the cylinder this thermometer d, is introduced, the stem of which is protected by a piece of brass tubing. We thus obtain the temperature of the mercury. The flat end of the cylinder is to be turned towards the sun, and the surface thus presented is coated with lampblack.
Sivu 19 - The divisions on this scale correspond exactly with those on the tube of the standard barometer. A vernier and telescope are made to slide on the scale by means of a rack and pinion. The telescope has two horizontal wires, one fixed and the other moveable by a micrometer screw, so that the difference between the height of the column of mercury and the nearest division on the scale of the standard, and also of all the other barometers placed by the side of it for comparison, can be measured either...
Sivu 81 - The result of this is that on the thermometer being set, the contracting force of the mercury in cooling withdraws the fluid in the indicating stem only, whilst on its expanding with heat the long column does not move, the increased bulk of mercury finding an easier passage through the larger bore into the small pear-shaped chamber attached.