Pneumatics |
From inside the book
Page 32
... mercury only , and so arranged that this mercury may be supported by atmospheric pressure ; all the other appendages being contrivances for pro- tecting the tube and ascertaining the exact height of the mercurial column . At first sight ...
... mercury only , and so arranged that this mercury may be supported by atmospheric pressure ; all the other appendages being contrivances for pro- tecting the tube and ascertaining the exact height of the mercurial column . At first sight ...
Page 33
... mercury , any admixture of them will cause the height of the barometer , as indicated by a column of the ... mercurial co- lumn at a lower level than if the Torricellian vacuum were perfect ; so that the observed height of the column ...
... mercury , any admixture of them will cause the height of the barometer , as indicated by a column of the ... mercurial co- lumn at a lower level than if the Torricellian vacuum were perfect ; so that the observed height of the column ...
Page 34
... mercury from escaping , for these are very pernicious if inhaled . The tube is first gently warmed , so as to ... mercurial column , its length exactly measures the atmospheric pressure whenever the temperature is too low for the ...
... mercury from escaping , for these are very pernicious if inhaled . The tube is first gently warmed , so as to ... mercurial column , its length exactly measures the atmospheric pressure whenever the temperature is too low for the ...
Page 37
... mercury from the tube , we may test its value by three indica- tions . First , by the brightness of the mercurial column , and the absence of any flaw , speck , or dulness of sur- face ; secondly , by the barometric light , as it is ...
... mercury from the tube , we may test its value by three indica- tions . First , by the brightness of the mercurial column , and the absence of any flaw , speck , or dulness of sur- face ; secondly , by the barometric light , as it is ...
Page 38
... mercurial column . With an increase of atmospheric pressure the mercury in the longer tube rises , and that in the short tube is depressed , together with the float , and this gives a small motion of revolu- tion to the pulley , and ...
... mercurial column . With an increase of atmospheric pressure the mercury in the longer tube rises , and that in the short tube is depressed , together with the float , and this gives a small motion of revolu- tion to the pulley , and ...
Other editions - View all
Common terms and phrases
30 inches 30th parallel air-pump ascending atmo atmospheric pressure ATMOSPHERIC TIDE barometer becomes bodies boiling bulk capillarity carbonic acid cold colder column of water condensed constant contrary cooler density descends diminished direction Drôme duced earth earth's surface easterly effect elastic force equal equator equatorial expansion filled fluid gales geometrical progression glass half heat hemisphere Hence inches of mercury inclosed increase instrument land breeze latitude length less limb liquid lower current mean measure mercurial column metal miles an hour monsoons motion mountain moving northern hemisphere number of vibrations Nyons observations open end oscillations particles pipe piston polar polar circle portion of air portion of mercury produced Professor Daniell proportional pump quantity rarefaction rarefied regions rise scale sea breezes sea-level siphon solids sound space string supposed temperate zones tion trade-winds tropics tube upper current upwards vacuum valve velocity vessel warmer westerly wind windward and leeward
Popular passages
Page 108 - 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 65 - Mexico, and, by heating the land violently, cause the air to rise over it. But the vacuum is filled up not only from the northward, but by the comparatively cold air of the equatorial regions in the neighbourhood.
Page 72 - Maryland, New Jersey, and New York on the 17th ; off George's Bank and Cape Sable on the 18th ; and over the Porpoise and Newfoundland Banks on the 19th of the same month ; having occupied about...
Page 14 - ... 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 61 - Trade on the other side of the equator. When the comparatively slow-moving air of the temperate zone, caused by the rotatory motion of the earth to the east, first comes into contact with the...
Page 65 - Monsoons are periodical currents of air 600116 ? which in the Arabian, Indian, and China seas blow for nearly six months of the year in one direction, and for the other six in a contrary direction. They are called monsoons from an Arabic word signifying season ; they are also called periodical winds, to distinguish them from the trade-winds which are constant.
Page 38 - The most popular form is the common wheel-barometer, as it is called. In this instrument the tube, instead of terminating at the bottom in a cistern, is recurved, so as to form an inverted siphon. As a rise of the mercury in the longer or closed limb is equivalent to a fall in the shorter limb, and vice versa, a float is placed on the surface of the mercury in the shorter limb, and is connected with a string passing over a pulley, and very nearly balanced by another weight on the other side of the...
Page 66 - ... drawn to, which gives them an easterly character; and this combined with their proper motion, if I may so call it, from the north, produces the north-east monsoon. There...
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 37 - By the barometric light, as it is called, or flashes of electric light in the Torricellian vacuum, produced by the friction of the mercury against the glass, when the column is made to oscillate through an inch or two in the dark ; 3.