Two Essays: One Upon Single Vision with Two Eyes; the Other on DewA Constable and Company, 1818 - 439 pages Contains possibly the first statement of the theory of natural selection; as well as the theory of dew and a classic work in meteorology and in environmental and industrial medicine and vision. |
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acquired admission admitted afterwards apothecaries appear atmosphere attract dew body by-law calm night cause Charlestown circumstances clear and calm clouds cold college of Physicians colour common axis conduct consequence considerable cornea Court of King's degree distance earth equal Essay examination exist experiments exposed fact feet formation of dew former frequently glass grains of wool grass grassplat greater ground hoarfrost honour horopter inches inns of court King's Bench latter learned left eye less licentiates London Lord Lord Mansfield Lordship mandamus ment mentioned metal moisture motion never object observed occasion occurred opinion optic axes pans person physicians placed plane possess present produced profession proposed racter radiation raised board rays reason received refractive regarded respect retina right eye serene night side similar situation sky at night snow Stanger substances supposed surface swandown temperature thermometer tion visible direction vision visual base warmer
Popular passages
Page 403 - ... by the decision of the Court of King's Bench, in the case of...
Page 206 - Dense clouds, near the earth, must possess the same heat as the lower atmosphere, and will therefore send to the earth, as much, or nearly as much heat as they receive from it by radiation. But similarly dense clouds, if very high, though they equally intercept the communication of the earth with the sky, yet being, from their elevated situation, colder than the earth, will radiate to it less heat than they receive from it, and may, consequently, admit of bodies on its surface becoming seyeral degrees...
Page 436 - Africa, some one would be better fitted than the others to bear the diseases of the country. This race would consequently multiply, while the others would decrease ; not only from their inability to sustain the attacks of disease, but from their incapacity of contending with their more vigorous neighbours. The colour of this vigorous race I take for granted, from what has been already said, would be dark. But the same disposition to form varieties still existing, a darker and a darker race would...
Page 215 - ... grass was surrounded by a hollow cylinder. VIII. An observation closely connected with the preceding, namely, that in clear and still nights frosts are less severe upon hills than in neighbouring plains,* has excited more attention, chiefly from its contradicting what is commonly regarded an established fact, that the cold of the atmosphere always increases with the distance from the earth.
Page 252 - I had often, in the pride of half knowledge, smiled at the means frequently employed by gardeners, to protect tender plants from cold, as it appeared to me impossible, that a thin mat, or any such flimsy substance, could prevent them from attaining the temperature of the atmosphere, by which alone I thought them liable to be injured. But, when I had learned, that bodies on the surface of the earth become, during a still and serene night, colder than the atmosphere, by radiating their heat to the...
Page 213 - Bodies, exposed in a clear night to the sky, must radiate as much heat to it during the prevalence of wind, as they would do if the air were altogether still. But in the former case, little or no cold will be observed upon them above that of the atmosphere, as the frequent application of warm air must quickly return a heat equal, or nearly so, to that which they had lost by radiation. A slight agitation of the air is sufficient to produce some effect of this kind ; though, as has already been said,...
Page 123 - I was led in the autumn of 1784, by the event of a rude experiment, to think it probable that the formation of dew is attended with the production of cold. In 1788, a paper on hoar-frost, by Mr. Patrick Wilson, of Glasgow, was published in the first volume of the Transactions of the Royal Society of Edinburgh, by which it appeared that this opinion bad been entertained by that gentleman before it had occurred to myself.
Page 405 - ... impolitic, but would also be a very wicked thing; if every such law were a snare for the conscience of the subject. But in these cases the alternative is offered to every man ; " either abstain from this, or submit to such a penalty:" and his conscience will be clear, whichever side of the alternative he thinks proper to embrace.
Page 139 - Thus, 10 grains of wool, placed upon the spot of the grassplat, which was directly under the middle of the raised board, and which enjoyed, therefore, a considerable oblique view of the sky, acquired during one night 7, during a second 9, and during a third 12 grains of moisture, while the quantities gained, during the same times, by equal parcels of wool, laid upon another part of the grassplat, which .was entirely exposed to the heavens, were 10, 16, and 20 grains.
Page 129 - I have frequently felt grass moist, in dry weather, several hours before sunset. On the other hand, I have scarcely ever known dew to be present in such quantity upon grass, as to exhibit visible drops, before the sun was very near the horizon, or to be very copious, till some time after sunset.