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Experiment solitary touching the nature of air.
866. STAR-LIGHT nights, yea, and bright moonshine nights, are colder than cloudy nights. The cause is, the dryness and fineness of the air, which thereby becometh more piercing and sharp; and therefore great continents are colder than islands : and as for the moon, though itself inclineth the air to moisture, yet when it shineth bright, it argueth the air is dry. Also close air is warmer than open air ; which, it may be, is, for that the true cause of cold is an expiration from the globe of the earth, which in open places is stronger; and again, air itself, if it be not altered by that expiration, is not without some secret degree of heat; as it is not likewise without some secret degree of light: for otherwise cats and owls could not see in the night; but that air hath a little light, proportionable to the visual spirits of those creatures. Experiments in consort touching the eyes and sight. 867. THE
eyes do move one and the same way; for when one eye moveth to the nostril, the other moveth from the nostril. The cause is motion of consent, which in the spirits and parts spiritual is strong. But yet use will induce the contrary; for some can squint when they will: and the common tradition is, that if children be set upon a table with a candle behind them, both eyes will move outwards, as affecting to see the light, and so induce squinting.
868. WE see more exquisitely with one eye shut, than with both open. The cause is, for that the spirits visual unite themselves more, and so become stronger. For you may see, by looking in a glass, that when you shut one eye, the pupil of the other eye that is open dilateth.
869. THE eyes, if the sight meet not in one angle, see things double. The cause is, for that seeing two things, and seeing one thing twice, worketh the same effect : and therefore a little pellet held between two fingers laid across, seemeth double.
870. PORE-BLIND men see best in the dimmer lights; and likewise have their sight stronger near hand,
than those that are not pore-blind; and can read and write smaller letters. The cause is, for that the spirits visual in those that are pore-blind, are thinner and rarer than in others; and therefore the greater light disperseth them. For the same cause they need contracting; but being contracted, are more strong than the visual spirits of ordinary eyes are; as when we see through a level, the sight is the stronger; and so is it when you gather the eye-lids somewhat close: and it is commonly seen in those that are pore-blind, that they do much gather the eye-lids together. But old men, when they would see to read, put the paper somewhat afar off: the cause is, for that old mens spirits visual, contrary to those of pore-blind men, unite not, but when the object is at some good distance from their eyes.
871. MEN see better, when their eyes are overagainst the sun or a candle, if they put their hand a little before their eye. The reason is, for that the glaring of the sun or the candle doth weaken the eye; whereas the light circumfused is enough for the perception. For we see that an over-light maketh the eyes dazzle; insomuch as perpetual looking against the sun would cause blindness. Again, if men come out of a great light into a dark room; and contrariwise, if they come out of a dark room into a light room, they seem to have a mist before their eyes, and see worse than they shall do after they have stayed a little while, either in the light or in the dark. The cause is, for that the spirits visual are, upon a sudden change, disturbed and put out of order; and till they be recollected, do not perform their function well. For when they are much dilated by light, they cannot contract suddenly; and when they are much contracted by darkness, they cannot dilate suddenly. And excess of both these, that is, of the dilatation and contraction of the spirits visual, if it be long, destroyeth the eye. For as long looking against the sun or fire hurteth the eye by dilatation ; so curious painting in small volumes, and reading of small letters, do hurt the eye by contraction.
872. It hath been observed, that in anger the eyes wax red; and in blushing, not the eyes, but the ears, and the parts behind them. The cause is, for that in anger the spirits ascend and wax eager; which is most easily seen in the eyes, because they are translucid ; though withal it maketh both the cheeks and the gills red; but in blushing, it is true the spirits ascend likewise to succour both the eyes and the face, which are the parts that labour : but then they are repulsed by the eyes, for that the eyes, in shame, do put back the spirits that ascend to them, as unwilling to look abroad: for no man in that passion doth look strongly, but dejectedly; and that repulsion from the eyes diverteth the spirits and heat more to the ears, and the parts by them.
873. The objects of the sight may cause a great pleasure and delight in the spirits, but no pain or great offence; except it be by memory, as hath been said. The glimpses and beams of diamonds that strike the eye; Indian feathers, that have glorious colours ; the coming into a fair garden ; the coming into a fair room richly furnished; a beautiful person ; and the like; do delight and exhilarate the spirits much. The reason why it holdeth not in the offence is, for that the sight is the most spiritual of the senses ; whereby it hath no object gross enough to offend it. But the cause chiefly is, for that there be no active objects to offend the eye. For harmonical sounds, and discordant sounds, are both active and positive: so are sweet smells and stinks : so are bitter and sweet in tastes : so are over-hot and over-cold in touch : but blackness and darkness are indeed but privatives; and therefore have little or no activity. Somewhat they do contristate, but very little. Experiment solitary touching the colour of the sea,
or other water. 874. WATER of the sea, or otherwise, looketh blacker when it is moved, and whiter when it resteth. The cause is, for that by means of the motion, the beams of light pass not straight, and therefore must be
darkened; whereas, when it resteth, the beams do pass straight. Besides, splendour hath a degree of whiteness; especially if there be a little repercussion : for a looking-glass with the steel behind, looketh, whiter than glass simple. This experiment deserveth to be driven farther, in trying by what means motion may hinder sight.
Experiment solitary touching shell-fish. 875. SHELL-FISH have been, by some of the ancients, compared and sorted with the insecta; but I see no reason why they should ; for they have male and female as other fish have: neither are they bred of putrefaction ; especially such as do move. Nevertheless it is certain, that oisters, and cockles, and mussels, which move not, have no discriminate sex. Query, in what time, and how they are bred ? It seemeth, that shells of oisters are bred where none were before; and it is tried, that the great horse-mussel, with the fine shell, that breedeth in ponds, hath bred within thirty years: but then, which is strange, it hath been tried, that they do not only gape and shut as the oisters do, but remove from one place to another. Experiment solitary touching the right side and the
left. 876. The senses are alike strong, both on the right side and on the left; but the limbs on the right side are stronger. The cause may be, for that the brain, which is the instrument of sense, is alike on both sides; but motion, and abilities of moving, are somewhat holpen from the liver, which lieth on the right side. be also, for that the senses are put in exercise indifferently on both sides from the time of our birth; but the limbs are used most on the right side, whereby custom helpeth; for we see that some are left-handed; which are such as have used the left hand most.
Experiment solitary touching frictions. 877. FRICTIONS make the parts more fleshy and full; as we see both in men, and in currying of horses, etc. The cause is, for that they draw greater quantity
of spirits and blood to the parts: and again, because they draw the aliment more forcibly from within : and again, because they relax the pores, and so make better passage for the spirits, blood, and aliment: lastly, because they dissipate and digest any inutile or excrementitious moisture which lieth in the flesh; all which help assimilation. Frictions also do more fill and impinguate the body, than exercise. The cause is, for that in frictions the inward parts are at rest; which in exercise are beaten, many times, too much : and for the same reason, as we have noted heretofore, galley-slaves are fat and fleshy, because they stir the limbs more, and the inward parts less. Experiment solitary touching globes appearing flat
at distance. 878. ALL globes afar off appear flat. The cause is, for that 'distance, being a secondary object of sight, is not otherwise discerned, than by more or less light; which disparity, when it cannot be discerned, all seemeth one: as it is, generally, in objects not distinctly discerned; for so letters, if they be so far off as they cannot be discerned, shew but as a duskish paper; and all engravings and embossings, afar off, appear plain.
Experiment solitary touching shadows. 879. THE uttermost parts of shadows seem ever to tremble. The cause is, for that the little motes which we see in the sun do ever stir, though there be no wind; and therefore those moving, in the meeting of the light and the shadow, from the light to the shadow, and from the shadow to the light, do shew the shadow to move, because the medium moveth.
Experiment solitary touching the rolling and break
ing of the
seas. 880. SHALLOW and narrow seas break more than deep and large. The cause is, for that, the impulsion being the same in both, where there is greater quantity of water, and likewise space enough, there the