16. As whiteness is light, so blackness is the privation of light, or darkness. And, from hence it is, first, that all holes, from which no light can be reflected to the eye, appear black. Secondly, that when a body hath little eminent particles erected straight up from the superficies, so that the beams of light which fall upon them are reflected not to the eye but to the body itself, that superficies appears black; in the same manner as the sea appears black[black] when ruffled by the wind. Thirdly, that any combustible matter is by the fire made to look black before it shines. For the endeavour of the fire being to dissipate the smallest parts of such bodies as are thrown into it, it must first raise and erect those parts before it can work their dissipation. If, therefore, the fire be put out before the parts are totally dissipated, the coal will appear black; for the parts being only erected, the beams of light falling upon them will not be reflected to the eye, but to the coal itself. Fourthly, that burning glasses do more easily burn black things than white. For in a white superficies the eminent parts are convex, like little bubbles; and therefore the beams of light, which fall upon them, are reflected every way from the reflecting body. But in a black superficies, where the eminent particles are more erected, the beams of light falling upon them are all necessarily reflected towards the body itself; and, therefore, bodies that are black are more easily set on fire by the sun beams, than those that are white. Fifthly, that all colours that are made of the mixture of white and black proceed from the different position of the particles that rise above the superficies, and their different forms of asperity. For, according to these differences, more or fewer beams of light are reflected from several bodies to the eye. But in regard those differences are innumerable, and the bodies themselves so small that we cannot perceive them; the explication and precise determination of the causes of all colours is a thing of so great difficulty, that I dare not undertake it.
Vol. I. Lat. & Eng.
C. XXVII.
Fig. 1-2]
| [Fig 1] | [Fig 2] |
CHAPTER XXVIII.
OF COLD, WIND, HARD, ICE, RESTITUTION OF
BODIES BENT, DIAPHANOUS, LIGHTNING AND
THUNDER; AND OF THE HEADS OF RIVERS.
[1.] Why breath from the same mouth sometimes heats and sometimes cools.—[2.] Wind, and the inconstancy of winds, whence.—[3] Why there is a constant, though not a great wind, from east to west, near the equator.—[4.] What is the effect of air pent in between the clouds.—[5.] No change from soft to hard, but by motion.—[6.] What is the cause of cold near the poles.—[7.]. The cause of ice; and why the cold is more remiss in rainy than in clear weather. Why water doth not freeze in deep wells as it doth near the superficies of the earth. Why ice is not so heavy as water; and why wine is not so easily frozen as water.—[8.] Another cause of hardness from the fuller contact of atoms; also, how hard things are broken.—[9.] A third cause of hardness from heat.—[10.] A fourth cause of hardness from the motion of atoms enclosed in a narrow space.—[11.] How hard things are softened.—[12.] Whence proceed the spontaneous restitution of things bent.—[13.] Diaphanous and opacous, what they are, and whence.—[14.] The cause of lightning and thunder.—[15.] Whence it proceeds that clouds can fall again after they are once elevated and frozen.—[16.] How it could be that the moon was eclipsed, when she was not diametrically opposite to the sun.—[17.] By what means many suns may appear at once.—[18.] Of the heads of rivers.
Why breath from the same mouth sometimes heats and sometimes cools.