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coagulated an infinite number of small sugar particles upon the greater, and those were so exceedingly small, that a thousand of them together were not so large as one of those particles before represented, which was itself not so large as a single grain of sand. Now since we see that from one and the same matter two different figures are coagulated, it is easy to conceive that several other figures might be produced in the first coagulation, especially when any of the parts of those little bodies lie upon each other; and therefore, also, we should not wonder, to see, in the coagulation of salts, several figures produced out of one particle of salt.

On the Usefulness of the Silk of Spiders. By M. Bon,

P.R.S. of Montpelier. - [1710.] SPIDERS make a silk as beautiful, strong, and glossy, as common silk: the prejudice entertained against so common and despicable an insect is the reason that the public has been hitherto ignorant of its usefulness. Even common silk, as considerable as it is, was long unknown, and was neglected after its discovery. It was in the island of Coos, that Pamphila, daughter of Platis, first discovered the manner of working it. This discovery became soon after known to the Romans, who brought their silk from the country of the Seres, a people of Scythia in Asia, near the mountain Imaus, where silk-worms naturally breed; but far from deriving any advantage from so useful a discovery, they could never imagine these worms should produce so beautiful and valuable a thread, and made many chimerical conjectures about it. So that in consequence of their ignorance and idleness silk was for several ages so very scarce, that it was sold for its weight in gold; and Vopiscus relates, that for this reason the Emperor Aurelian refused his empress a suit of silks though she earnestly desired it. Its scarcity continued a long time, and it was to the monks at last that we owe the manner of breed. ing silk-worms, who brought their eggs from Greece, under the reign of the Emperor Justinian, as we learn from Godefridus, in his notes on the Code; and Ulpian assures us, that the price of silk was equal to that of pearls. It was late before France enjoyed the benefit of this discovery ; when Henry II. brought to the marriages of his daughter and sister the first silk stockings that were seen in his kingdom. To him and his successors we owe the establishment of this manufacture at Tours and Lyons, which has made silk so

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common, and has so greatly increased the magnificence of furniture and clothes.

The ingenious fable of. Arachne shows us, that it is to the spider we owe the first hints of weaving cloth, and laying nets for animals ; so the advantage which may arise from this insect will perhaps make it hereafter be esteemed as highly as silk-worms and bees.

I shall reduce all the different sorts of spiders to two prin. cipal kinds, viz. such as have long legs, and such as have short ones: the latter of which furnishes the silk I am now speaking of. In respect of their particular differences, they are distinguished by their colour ; some being black, others brown, yellow, green, white; and some again of all these several colours mixed together. They differ also in the number and position of their eyes, some having six, others eight, and some ten, differently placed on the top of the head, as may easily be seen by the naked eye, but much better by the help of a glass. They are alike in other respects, as in their body, which nature has divided into two parts; the fore part is covered with a shell, or hard scale, set with hairs ; it contains the head and breast, to which are fixed its eight legs, each of them consisting of six joints; they have also two other legs, which may be called their arms, and two claws, armed with two crooked nails, and joined by articulations to the extremity of the head ; with these claws they kill the insects they feed on, their mouth being immediately underneath them. They have two small nails at the end of each leg, and a spongy substance between them, which is doubtless of service to them when they go upon smooth bodies.

All spiders spin their threads from the anus, about which there are five papillæ, or small nipples, which at first sight one would take for so many spindles, that serve to form the thread; I have found these papillæ to be muscular, and furnished with a sphincter. A little within these I have observed two others, from the middle of which issue several threads, in a pretty large quantity, sometimes more, and sometimes less, which the spiders make use of after a very mechanical manner, when they want to go from one place to another : they hang themselves perpendicular by a thread, and turning their head towards the wind, they shoot several others from their anus, like so many darts ; and if by chance the wind, which spreads them abroad, fastens them to any solid body, which they perceive by the resistance they find in drawing them in from time to time with their feet, they

then make use of this kind of bridge, to pass to the place where their threads are fixed. But if these threads meet with nothing to fix on, the spiders continue to let them out further, till their great length, and the force with which the wind drives them, surpassing the weight of their bodies, they find themselves to be strongly drawn; and then breaking the first thread, which they hung by, they let themselves loose to be driven by the wind, and flutter on their backs in the air with their legs stretched out. And by these two ways it is, that they pass over roads, streets, and the broadest rivers, as in the engraving.

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One may himself wind up these threads, which, by reason of their being united together, seem to be but one when they are about a foot in length; but I have distinguished them into 15 or 20 at their issuing from the anus. What is further remarkable, is the ease with which this insect moves its anus every way, by means of the many rings that border upon it. This is absolutely necessary for them, in order to wind up their threads or silk, which in the female spider is of two sorts. The first thread that they wind is weak, and serves them for no other use than to make that sort of web, in which they catch flies. The second is much stronger : in this they wrap up their eggs, and by this means preserve them from the cold, and secure them from such insects as would destroy them. These last threads are wrapped very loosely about their eggs, and resemble in form the bags of silk-worms, that have been prepared and loosened between the fingers, in order to be put upon the distaff,

These spiders' bags are of a grey colour when new, but turn blackish when long exposed to the air. It is true, one may find several other spiders' bags of different colours, and that afford a better silk, especially those of the tarantula ; but their scarcity would render it very difficult to make experiments upon them ; so that we must confine ourselves to the bags of such spiders as are most common, which are the short-legged ones. These always find out some place, secure from the wind and rain, to make their bags in ; as hollow trees, the corners of windows or vaults, or under the eaves of houses. And by getting together a great many of these bags, it was that I made this new silk, which is nowise inferior in beauty to common silk. It easily takes all sorts of colours; and one can as well make large pieces of it as stockings and gloves, which I have done.

We could breed spiders as they do silk-worms; for they multiply much more, and every spider lays 600 or 700 eggs; whereas the papilios, or flies of silk-worms, lay only about 100; and of this number we must abate at least half, on account of their being subject to several diseases, and are so tender, that the least matter hinders them from making their bags. Spider-bags, on account of their lightness, yield much more silk than the others; as a proof of which, 13 oz. yield near 4 oz. of clean silk; 3 oz. of which will make a pair of stockings for the largest-sized man: those I have made weigh only 2 oz. and a quarter, and the gloves about threequarters of an ounce; whereas stockings of common silk weigh 7 or 8 oz. .

It is certain that a great advantage may be made of this insect, which has always been thought troublesome and dangerous, on account of its venom: but I confidently assert, that spiders are not venomous; having been very often bitten by them myself, without any ill consequence. And as for their silk, it is so far from having any venom, that every body makes use of it to stop bleeding, and heal cuts; and, indeed, its natural gluten is a kind of balsam, that cures small wounds, by defending them from the air.

Experiments on Fishes kept in Water, under different Circum

stances. By Mr. FR. HAUKSBEE, F.R.S. - [1712,] The fishes used in the following experiments were gudgeons; which are naturally very brisk and lively in the water, and can live a considerable time out of it. I put three into a glass vessel with about three pints of common water : these fishes were to be a standard to compare the others by. Into another glass I put three more to a like quantity of water, which just filled it; I then screwed down a brass plate with a leather between, to prevent a communication with the water in the glass and the external air; and that it might the better resemble a pond of water frozen over, on which account this experiment was made, I suffered as little air as possible to remain on the surface of the included water. The third glass had a like quantity of water, which first by boiling, then by continuing it a whole night in vacuo on the air-pump, was completely deprived of its air: into this water, also, I put the same number of gudgeons as into the former, and then waited the event.

It was about half past ten o'clock in the morning when I began the experiments, and in about half an hour from that time, the fishes in the exhausted water, or water deprived of its air, began to discover some uneasiness by a more than ordinary motion in their mouths and gills, or respiration, if I may call it so, differing from the fishes in the other glasses, which at the same time showed no alteration: only I observed that they would now and then ascend to the top of the water, but suddenly swim down again; and in this state they continued for some considerable time, without any sensible alteration.

About five hours after the last observation, the fishes in the exhausted water became not so active, on a motion given to the glass that contained them, as before; and the gudgeons included without any communication with the outward air now began considerably to abate of their vivacity. At seven in the evening the included fishes lay all at the bottom of the glass, with their bellies upwards ; nor on shaking the glass could I put them in motion, or cause them to stir their fins or tail, only I could observe a motion in their mouths, which showed they were not quite dead. In this state they lay for some time; but considering the experiment would not be complete, if I did not attempt their recovery by taking off the brass cover, being very certain they must have died in some small time under the circumstances they were in, I took off the cover, and gave the surface of the water a free and

open communication with the external air. At about ten at night I observed them again, when their recovery was so evident, that on a little disturbing the glass that contained them, they were actually in motion again ; and at this time, also, the fishes in the water deprived of air began to appear more brisk and lively than at the last observation.

Here I cannot but take notice, that though the water was

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