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30 inches air-gun air-pump amount anemometer anemoscope arithmetical progression ascending atmospheric pressure barometer-tube barrel blow bodies bottom breeze bulk capillarity carbonic acid cistern coincide column of mercury column of water compressed condensed air constant containing cylinder density depression descends diameter diminished direction effect elastic force equal equator exactly exhausting expand feet filled fluid gases gauge geometrical progression glass greater heat height hemisphere inches of mercury increase instrument land breeze latitude length liquid lower means measure mercurial column mercury rises metal miles an hour monsoons motion move Natural Philosophy neutral point number of vibrations observations oscillations particles pencil piston produce Professor Daniell proportion quantity rarefaction rise scale screw siphon solids sound space specific gravity spring square inch stop-cock supposed syringe temperature tion trade-winds tube upper current upwards vacuum valve velocity vernier vessel vibrations per second warmer wind windward and leeward
Page 118 - The wind goeth toward the south, and turneth about unto the north; it whirleth about continually, and the wind returneth again according to his circuits.
Page 13 - ... pressures counterbalance each other. In the same manner the fluid atmosphere presses equally in all directions, and the human body immersed in it may be compared to a sponge plunged into deep water ; it is not crushed, because the water fills the cavities of the sponge, and also surrounds it entirely. In like manner our bodies, and even our bones, are filled either with liquids capable of sustaining pressure, or with air of the same density as the external air, so that the outward is counteracted...
Page 77 - They blow for nearly six months of the year in one direction, and for the other six in an opposite direction. The Malays call them mooseen, which signifies season.
Page 137 - SHEET of plain paper, placed in the instrument, under a registering pencil, is moved forward by rotating, hemispherical fans, at the rate of one inch for every ten miles of air that passes ; this same pencil, having a lateral motion given to it by a vane, records the point of the compass from which the wind blows, and a clock-hammer, descending every hour, strikes its mark on the margin of the paper, to express the time. Thus, in a single line, are given the length of the current, its direction,...
Page 122 - ... to 16 or 32 points of the compass, and a mark left by the pencil upon one or more of these spaces, shows the direction of the wind. The pencil has two motions, the first from above downwards, and this increases in rapidity as the wind blows more strongly, and by the extent of its depression registers the whole amount of wind that has been blowing. The second motion depends on the changes in the direction of the wind ; and the pencil and its frame being carried round by the vane, the direction...
Page 30 - ... is equal to the level of the end of the tube above the level of the water in the air vessel ; and until the pressure of the condensed air exceeds what is necessary for this purpose, no water can spout from the end of the hose ; and...
Page 24 - The motion of the pistons is effected by means of a short crank with a jointed connecting-rod, converting the circular motion given by the lever handle into a vertical one, which is maintained by means of a cross-head, with rollers working between guides.
Page 4 - Combustion. greater in summer than in winter, and during night than during day. It is also rather more abundant in elevated situations, as on the summits of high mountains, than in plains ; this is probably owing to an absorption of the gas near the surface of the earth by plants and moist surfaces.
Page 132 - Greenwich during the former year was 18"7, and during the latter, 18-3 miles an hour, for the whole integrals of wind for those years, (as shown by the length of their type line, measured along all its windings,) was in 1841 no less than 167,322 miles, and in 1842, 159,950 miles; showing that the whole movement of the air in this country is about four times as great as its resultant or effective movement. The more variable the wind may be at any place, the smaller...
Page 119 - ... it is not necessary to notice them here, further than to state, that in most of these contrivances the velocity of the wind was measured by its mechanical effects. The compression of a spiral spring, the elevation of a weight round a centre acting at the arm of a variable lever, were the chief means employed to balance, and consequently to measure, the force of the wind. The spring, however, which, * From avisos, the wind, and /tfrpov, a measure. We are indebted for this essay chiefly to the...