Hygrometry, and the construction and uses of a new hygrometer. On the radiation and absorption of heat in the atmosphere. On the water-barometer erected in the hall of the Royal society. On climate: considered with regard to horticulture. Remarks upon the barometer and thermometer, and the mode of using meteorological instruments in general. On the gradual deterioration of barometers, and the means of preventing the same. On the climate of London. Abstracts of meteorological observations. On some of the phenomena of atmospheric electricity

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Page 124 - often endeavoured to measure the power of the sun between the tropics, by two thermometers of mercury perfectly equal, one of which remained exposed to the sun, while the other was placed in the shade. The difference resulting from the absorption of the rays in the ball of the instrument never exceeded 3-7 (6-6 Fahr.); sometimes it did not even rise higher than one or two degrees.
Page 225 - A portion of a grass plat under the protection of a tree or hedge will generally be found, on a clear night, to be eight or ten degrees warmer than surrounding unsheltered parts ; and it is well known to gardeners that less dew and frost are to be found in such situations than in those which are wholly exposed.
Page 150 - It should be allowed to do so for three or four minutes before the observation begins, taking care, however, not to let it mount into the bulb, by a proper use of the screw. At the same time the tube should be carefully cleared (by the same action) of all small broken portions of liquid remaining in it, which should all be drawn down into the bulb. When all is ready for observation, draw the liquid down to zero of its scale, gently and steadily ; place it on its stand, with its screen before it,...
Page 158 - ... that intensity of solar radiation which at a vertical incidence, and supposing it wholly absorbed, would suffice to melt one millionth part of a metre in thickness from the surface of a sheet of ice horizontally exposed to its action per minute of mean solar time...
Page 220 - Excessive exhalation is very injurious to many of the processes of vegetation, and no small proportion of what is commonly called blight may be attributed to this cause. Evaporation increases in a prodigiously rapid ratio with the velocity of the wind, and anything which retards the motion of the latter, is very efficacious in diminishing the amount of the former ; the same surface, which in a calm state of the air would exhale 100 parts of moisture, would yield 125 in a moderate breeze, and 150...
Page 161 - ... as many eclipses invisible or insignificant in one locality, are great, or even total in others. The observations should commence an hour at least before the eclipse begins, and be continued an hour beyond its termination, and the series should be uninterrupted, leaving to others to watch the phases of the eclipse. The atmospheric circumstances should be most carefully noted during the whole series.
Page 224 - Any portion of the surface of the globe which is fully turned towards the sun receives more radiant heat than it projects, and becomes heated ; but when, by the revolution of the axis this portion is turned from the source of heat, the radiation into space still continues, and being uncompensated, the temperature •declines. In consequence of the different degrees in which different bodies possess this power of radiation, two contiguous portions of the system of the earth will become of different...
Page 122 - Scoresby, in his account of the arctic regions, observes that when the sun's rays "fall upon the snow-clad surface of the ice or land, they are in a great measure reflected, without producing any material elevation of temperature; but when they impinge on the black exterior of a ship, the pitch on one side occasionally becomes fluid while ice is rapidly generated at the other.
Page 230 - ... are always more abundant in the former than in the latter situations. It is not meant to include in this observation, places surrounded by lofty and precipitous hills which obstruct the aspect of the sky, for in such, the contrary effect would be produced. Gentle slopes, which break the undulations of the air, without naturally circumscribing the heavens, are...
Page 31 - They vary on the land and on the water ; they vary in sun-shine and in the shade ; they vary as land is more or less clothed with vegetation, or as water is more or less deep. The evaporating gauge, so far from representing the circumstance of...

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