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which was the least in sap, at the time it was barked, discovered the first symptoms of a disorder, likely to prove its destruction in a short time. Its leaves began to turn yellow on the south side, and soon after became quite so, and dropped off dry, so that on the 26th of August there was not one left. I had it cut down the 30th of the same month, being myself upon the spot. It was become so hard, that a wedge could scarcely enter it, and so brittle that a slight stroke of the beetle was sufficient to shatter it. The blea* appeared harder than the heart of the wood, which was still moist and full of juice.

The tree which, next to this, was the most defective in sap at the time of barking, soon followed it; the leaves began to lose their verdure on the 13th of July, and lost it entirely before the 10th of September. As I suspected that the first had been felled too early, and that the moisture, I perceived within, shewed still some remains of life, I ordered it to stand, to see if it would produce any leaves the next spring.

My other four oaks held out vigorously; they dropped their leaves but a few days before the usual season; and one of them, whose head was but small, parted not with them before the natural time of falling; but I observed that the leaves, and even some of the shoots of all the four, were grown dry on the south side many days before.

The spring following, all these trees were beforehand with the rest, and were covered with verdure eight or ten days before the time. I took notice that the growth of the leaves was quick, but soon stinted for want of sufficient nourishment, however they kept alive; but the tree which was the first barked the foregoing year, underwent the full effect of the state of inanition and dryness, to which it was reduced; its leaves faded apace, and fell in the heats of July. I had it cut down the 30th of August, just a year after that which had preceded it. I judged that it would prove as hard at least in the blea as the other, and much harder in the heart, which now had hardly any moisture left. I had it placed under a shed, where the other already was, with the six trees in their bark, with which I designed to compare them.

Three of the four remaining trees parted with their leaves

By the word Blea is here understood the white softer part of the wood which lies between the bark and the heart: the London timber merchants and carpenters call it the sap.

the beginning of September, but that which had the small head retained them a good deal longer, and was not quite bare before the 22d of that month. I reserved it, together with that of the other four, which seemed the least sickly, for the year ensuing, and I ordered the two weakest to be felled in October. I left one of these trees exposed to the air and the injuries of the weather, and the others were placed under the shed; they proved very hard to the wedge, and the heart of the wood was very nearly dry.

In the ensuing spring, the two most vigorous of my reserved trees did still manifest some symptoms of life; the buds swelled, but the leaves did not unfold. The other seemed quite dead; and indeed having caused it to be felled in May, I found it had no radical moisture left, and it proved very hard both without and within. I had the last felled some time after, and both of them were placed under the shed, there to lie with the others for a new kind of trial. The better to compare the wood of the barked trees with that of ordinary wood, I took care to lay up all the six unbarked oaks together, with a barked one of the same size; for experience had already taught me, that the wood in a tree of a large size, was heavier and stronger than that in a tree of a less size, though of the same age. I caused all my trees to be sawed into pieces of 14 feet long; I marked centres on them at each end, and drew squares of 6 inches on all of them, and had the four faces sawed away, so that each of them became a beam of 14 feet long, and exactly 6 inches square. I had them reduced truly to these dimensions throughout their whole length, by carefully planing them. I caused four of each sort to be broken, to find their strength, and to be well assured, as I soon was, of the difference of each.

The beam made of the body of the tree, which died the first after the barking, weighed 242 pounds; it proved the weakest of all of them, and broke under 7240 pounds.

That of the tree in its bark, whigh-I compared with it, weighed 243 pounds: it broke under 7320 pounds.

The beam of the second barked tree weighed 249 pounds; it bent more than the former, and broke under the weight of 8862 pounds.

That of the tree in its bark which I compared with it, weighed 236 pounds; it broke under 7885 pounds.

The beam of the barked tree exposed to the injury of the weather, weighed 258 pounds; it bent still more than the second, and broke under 8926 pounds.

That of the tree in bark which I compared with it, weighed 238 pounds, and broke under 7420 pounds.

Lastly, the beam of the tree with the small head, which I had always thought the best, weighed 263 pounds, and broke with no less than 9046 pounds.

The tree which I compared it with, weighed 238 pounds, and broke under 7500 pounds.

The two other barked trees proved defective in the inside, where there were some knots, so that I would not break them but the trials above-mentioned sufficiently prove, that timber barked and dried standing, is always heavier and considerably stronger than timber kept in its bark. What I am going further to relate will put this matter quite out of doubt.

Of the top of the body of the tree, which was barked and exposed to the weather, I caused to be made a beam 6 feet long and 5 inches square; on one of its sides was discovered a small shake, which was not above half an inch deep, and on the opposite side a small stain about an inch broad, of wood that was browner than the rest. As these defects seemed not very considerable, I ordered it to be weighed and charged: its weight was 75 pounds; and in one hour and five minutes, being loaded with 8500 pounds, it gave a violent crack; I imagined it would break in a little time after the crack, which I had found hitherto was the case, but having waited patiently three hours, and finding that it neither gave way nor bent, I continued to increase the charge, and in about an hour more it broke, having kept cracking a quarter of an hour under a weight of 12,745 pounds. I should not have related this trial so particularly, only to shew, that but for its little defects on two of its sides, this beam would have sustained still more weight.

A beam just like this, formed out of the bottom of the body of one of the unbarked trees, weighed but 72 pounds; was very sound, without any defects; it was charged one hour and thirty-eight minutes, when it cracked very gently, and continued cracking once in about a quarter of an hour, for about three hours, and then broke, under a charge of 1189* pounds.

This experiment is much in favour of barked timber, for it shews that the wood of the upper part of the body of a barked tree, even with some defects, is heavier and stronger than the wood of the lower part of the body of an unbarked tree, without any defect.

1754, Feb.

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*Thus in the original; but I imagine the weight should be 11,089. E

VI. Method of preserving Books from the Depredations of Worms and Insects.

THERE is a very small insect that in the month of August lays its eggs in books, and especially in those leaves near the cover. From these eggs proceed a sort of mites, very like those bred in cheese, which change their state and become beetles, and when the time of transformation approaches, they endeavour to get air, and eat their way through till they have gained the extremity of the book.

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To give these mites a disrelish for books, the paste which the binders make use of, and which is supposed chiefly to attract them, has often been mingled with bitter substances, as wormwood, coloquintida, &c. without any success. Mineral salts, to which all insects have an aversion, afford the only remedy. The salt called arcanum duplicatum, allum and vitriol, are proper for this purpose. By mingling therefore a small quantity of any of these mineral salts in the paste, books will be effectually preserved from the attacks of all sorts of worms and insects.

M. Prediger, in his Instructions to Bookbinders, printed at Leipsic, in the German language, in 1741, says, that if binders were to make their paste of starch instead of flour, worms would not touch the books. He also directs pulve rised allum mixed with a little fine pepper, to be strewed between the book and the cover, and also upon the shelves of the library; and for the more effectual preservation of the books in libraries, he advises rubbing the books well, in the months of March, July, and September, with a woollen cloth dipped in powdered allum. And it were to be wished that for the future all bookbinders would make their paste in the manner recommended, but I would not advise depending upon starch without any admixture of mineral salts.

[It is remarkable, that worms seldom attack books printed on English made paper.]

1754, Feb.

VII. The Uncertainty of Human Testimony.

JAQUES DU MOULIN, a French refugee, having brought over his family and a small sum of money, employed it in

purchasing lots of goods that had been condemned at the Custom-house, which he again disposed of by retail; as these goods were such as having a high duty were frequently smuggled, those who dealt in this way were generally suspected of increasing their stock by illicit means, and smuggling, or purchasing smuggled goods, under colour of dealing only in goods that had been legally seized by the king's officers, and taken from smugglers. This trade, however, did not in the general estimation, impeach his honesty, though it gave no sanction to his character: but he was often detected in uttering false gold; he came frequently to persons of whom he had received money, with several of these pieces of counterfeit coin, and pretended that they were among the pieces which had been paid him; this was generally denied with great eagerness, but, if particular circumstances did not confirm the contrary, he was always peremptory and obstinate in his charge. This soon brought him into disrepute, and he gradually lost not only his business but his credit. It happened that having sold a parcel of goods, which amounted to seventy-eight pounds, to one Harris, a person with whom he had before had no dealings, he received the money in guineas and Portugal gold, several pieces of which he scrupled, but the man having assured him that he himself had carefully examined, and weighed those very pieces, and found them good, Du Moulin took them, and gave his receipt.

In a few days he returned with six pjeces, which he averred were of base metal, and part of the sum which he had a few days before received of him for the lot of goods; Harris examined the pieces, and told Du Moulin that he was sure they were none of them among those which he had paid him, and refused to exchange them for others. Du Moulin as peremptorily insisted on the contrary, alleging that he had put the money in a drawer by itself, and locked it up till he offered it in payment of a bill of exchange, and then the pieces were found to be bad, insisting that they were the same to which he had objected. The man now became angry, and charged Du Moulin with intending a fraud. Du Moulin appeared to be rather piqued than intimidated at this charge, and having sworn that these were the pieces he received of Harris, Harris was at length obliged to make them good; but, as he was confident Du Moulin had injured him by a fraud, supported by perjury, he told his story wherever he went, exclaiming against him with great bitterness, and met with many persons who had nearly the same complaints, and told him that it had been a practice of Du

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