The causes of heat and cold : in the several climates and situations of this globe, so far as they depend upon the rays of the sun, considered in order to shew that the difference of heat and cold in other countries may be nearly ascertained by a thermometer as it was read to the Royal Society / by T. Sheldrake.

  • Sheldrake, Timothy, -1770.
Date:
1756
Catalogue details

Licence: Public Domain Mark

Credit: The causes of heat and cold : in the several climates and situations of this globe, so far as they depend upon the rays of the sun, considered in order to shew that the difference of heat and cold in other countries may be nearly ascertained by a thermometer as it was read to the Royal Society / by T. Sheldrake. Source: Wellcome Collection.

    18/52 (page 10)
    ■ ’ ( 1° ) . the Surface of the Body is ragged or fmooth. Black abforbs Light, and if the Surface be rough, it will grow warm much fooner than if it were fmooth : White, on the contrary, re¬ flects Light and Heat, and that more vigoroufly from a poliflied Surface. Thi$ is the Reafon 4 why white Bodies are flower in taking Fire than thofe that are black. The fame holds true of all intermediate Degrees of Colour, in Proportion as they recede from the grand Op- pofites, black and white. If we walk on a black Sand, or dark dry Soil, our Feet will grow very warm from the Pleat that the Sand or Soil has imbibed from the Sun, but our Faces will feel little, if any Warmth reflected from the fame Soil: whereas if we walk on dry Chalk, white Sand, &c. our Feet will not acquire any confiderable Degree of Heat from them, but our Faces will feel, by a ftrong Re¬ flection of Light and Heat from fuch white Ground