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actinometer adjusted Admiral FitzRoy alcohol amount anemometer aneroid aneroid barometer ascertaining atmospheric pressure attached baro barometric column boiling-point bore bottom boxwood brass bulb cistern cold constructed contracted cylinder degree dial diameter difference Ditto ditto Drosometer electricity elevation evaporation fall feet fixed float fluid frame funnel gauge glass tube graduated heat height Hence horizontal hygrometer inches inches of mercury increase indications instru instrument International Exhibition 1862 invented ivory latitude limb liquid lower mahogany marine barometer maximum means measuring ment mercurial barometer mercurial column mercury falls Messrs metal meteorological meter millimetres minimum thermometer moisture mometer motion move needle Negretti and Zambra observation ordinary paper placed plate pointer portable position purpose quantity radiation rain reading rise scale screw self-registering solar radiation specific gravity standard barometer surface suspended sympiesometer syphon Table temperature tension upper vernier vertical weather wind zero
Page 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.
Page 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...
Page 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...
Page 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.
Page 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.
Page 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.
Page 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.
Page 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.
Page 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...
Page 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.