227. What is the chief cause of variation in the temperature of flowers?
It is generally supposed that their temperature is affected by their colours.
228. Why is it supposed that the colour of a flower influences its temperature?
Because it is found by experiment that the colours of bodies bear an important relation to their properties respecting heat, and hold some analogy to the relation of colours to light.
If when the ground is covered with snow, pieces of woollen cloth, of equal size and thickness, and differing only in colour, are laid upon the surface of the snow, near to each other, it will be found that the relation of colour to temperature will be as follows:—In a few hours the black cloth will have dissolved so much of the snow beneath it, as to sink deep below the surface; the blue will have proved nearly as warm as the black; the brown will have dissolved less of the snow; the red less than the brown; and the white the least, or none at all. Similar experiments may be tried with reference to the condensation of dew, &c. And it will be uniformly found that the colour of a body materially affects its powers of absorption and of radiation.
"And yet I say unto you, that even Solomon, in all his glory, was not arrayed like one of these."—Matt. vi.
229. Why do we know that these effects are not the result of light?