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iron nail; thus plainly beginning to resemble a plant*.

In like manner rust is produced on metals; scurf on glass, &c. from the dilatation of the native spirit, which swells, and drives the grosser parts before it; so as to thrust them out at the surface.+

It should be examined whether the earth swells on its surface, especially where the glebe lies spongy and hollow. There have sometimes been found trees, like the masts of ships, lying buried under ground, to the depth of several feet: whence it should seem, that such trees were once blown down by storms; and that the earth gradually raised itself over them.‡

The earth swells, manifestly, and suddenly, in earthquakes; at which time there frequently

This experiment seems not contingent but constant. And the curious microscopical observers have made several species of these kinds of superfotations, or vegetations upon Vegetables. See Mr. Boyle, Dr. Hook, Dr. Grew, thes French Memoirs, &c.

+ If the cause of rust were here justly assigned; ought not the same effect to happen in vacuo? The fact may deserve to be better enquired into; the several ways of making crocus martis considered; the composition and faults of glass examined, &c.

See the account of the generation of mosses, in the Philosophical Transactions. See also Mr. Evelyn's Sylvia.


burst forth springs of water; wreaths, and globes of flame; violent and strange winds; and stones and ashes are tossed into the air.

But all earthquakes are not sudden; for sometimes the earth continues in a tremor several days and in our time there was, in Herefordshire, a very small, gentle, and slow earthquake; wherein some acres of land continued gradually moving for a day together; and then transferred theniselves into another place, that lay not far off, upon a declivity: and there rested.†

It should be examined, whether the body of the waters does sometimes swell in the seas; for the flux of the sea must either happen, i. from a progressive motion; 2. the rising of the waters upwards, by some attractive virtue; or else, 3. from some tumefaction or relaxation in the waters themselves. And this latter, if it be any cause of the flowing of the sea, belongs to the present enquiryt.

The water swells and falls again in certain springs and wells; as if it were in the way of ebbing and flowing.

There also sometimes break out, in certain places, springs of water, without any preceding.

This kind of local motion, likewise said to happen in certain sandy desarts, requires to be further examined. * See the Novum Organum, part ii. aph. 36.

earthquake; and this in certain periods of years, from uncertain causes. Such eruptions of water generally happen in great droughts.

It should likewise be observed, that the seas sometimes swell out of the time of flood; and without any external wind: and that this generally precedes some great tempest or storm.


It is worth trying, whether some relaxation may not happen in the body of water, even in a small quantity. But to expose water to the sun or air, would rather consume it; therefore the experiment should be made in a close glass. For example, into a large bellied glass, having a long and slender neck, pour so much water as may fill the belly, and lower part of the stem. Let this be done in a dry season, when the wind stands northerly; and let the glass remain thus till the weather becomes rainy, and the wind southerly; then observe whether the water rises at all in the neck of the glass*. A careful enquiry should also be made about the swelling of water in wells; as, whether it happens more by night than day; and at what season of the year.

*See Novum Organum, part ii. aph, 13.


1. In rainy weather, the pegs of violins become swelled, and hard to screw; so likewise wooden drawers are harder to draw out, and doors with wooden hinges, harder to open in wet weather.

2. The strings of a violin are apt to break, when tight stretched in rainy weather.

3. The humours in the bodies of animals, are observed to be relaxed, to swell, to run, to oppress, and block up the pores most, in rainy weather, and southerly winds.

4. It is a received opinion, that the humours and juices, not only in animals, but also in plants, swell and fill up the cavities most about the full of the moon.

5. Salts dissolve, open, and dilate themselves in moist places; so likewise, in some measure, do sugar and sweat-meats: which are apt to grow mouldy, unless they stand in a room where fire is sometimes kept.

6. All things that have passed the fire, and are considerably shrunk, grow somewhat relaxed with time.

7. Diligent enquiry should be made into the tumefactions and relaxations of the air; and how far the causes of the wind depend upon them since vapours are neither commodiously


collected into rain, nor dissipated into clear air, without causing swells in the body of the air.*





FROM the heap of nature, we have above taken a few instances of the dilatation of bodies owing to their native spirit; whether in maturations, the first rudiments of generations, the excitations by motions, natural and preternatural irritations, or in putrefactions and relaxations: we next come to those openings and dilatations procured by fire, and actual external heat.


The relaxations of bodies by heat or fire, properly belong to the titles of heat and cold, the motion of dilatation, and those of separations, and alterations: but they must be touched under the present title; because, without a little knowledge of them, the enquiry of density and rarity cannot be well conducted.

* See the History of Winds, passiK.

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