neatly executed by a German; I was pleased in finding an old receipt, containing the secret by which this work is or probably may be effected; I send it you, not doubting but it will be agreeable to your ingenious readers, and that your publishing it may occasion the improvement or revival of the art, if lost to the English.

Method for preparing a liquor that will sink into and penetrate marble; so that a picture drawn on its surface, will appear also in its inmost parts.

TAKE of aqua-fortis, and aqua-regia, two ounces of each; of sal-ammoniac, one ounce; of the best spirit of wine, two drachms; as much gold as may be had for four shillings and six-pence; of pure silver, two drachms. These materials being provided, let the silver, when calcined, be put into a vial; and having poured upon it the two ounces of aquafortis, let it evaporate, and you will have a water, yielding first a blue, and afterwards a black colour: likewise, put the gold, when calcined, into a vial, and having poured the aqua-regia on it, set it by to evaporate; then pour the spirit of wine upon the sal-ammoniac, leaving it also to evaporate; and you will have a golden-coloured water, which will afford divers colours. And after this manner, you may extract many tinctures of colours out of other metals: this done, you may, by means of these two waters, paint what picture you please upon white marble of the softer kind, renewing the figure every day for some time with some fresh superadded liquor; and you will find that the picture has penetrated the whole solidity of the stone, so that cutting it into as many parts as you will, it will always represent to you the same figure on both sides.

Mr. Bird, a stone-cutter in Oxford, practised this art be fore the year 1660; several pieces of marble so stained by him are to be seen in Oxford; several others being shown to King Charles II. soon after the Restoration, they were broken in his presence, and found to correspond through the whole substance.

1747, Suppl.

Yours, &c.

J. B.

III. An Invention in Architecture, communicated by a person of distinction in Switzerland to an Italian Merchant.

A GENTLEMAN of small fortune, but well skilled in architecture, having drawn a plan of an intended building, which was to be for the most part of stone, shewed it to the most experienced workmen, in order to obtain a true notion of the expence. Their answer carried the cost much higher than he could either expect or afford; and, upon his inquiring particularly into the grounds of this expence, he was told that it arose from the ornaments he had designed, and the wages that must be paid to the stone-cutters.

This was a high mortification to our man of taste; he was unwilling to desert his plan, which had cost him so much trouble; and at last, after much thinking, a notion came into his head, that it might not be impossible to perform the mouldings on the cornices and entablements with planes. He tried the experiment with his own hands, and succeeded in hard and well seasoned stones, as well as those that were green and fresh from the quarry. Upon this, he applied himself to a joiner, shewed him what he would have done, and how it might be done; and the man, after a little trial, offered to do as much for six livres, as in the ordinary method would have cost twenty crowns. But upon a view of the invention, the mason he intended to employ took the task off his hands, and, by the help of a wooden press, of a very simple and easy construction, after preparing the stones, by taking off their loose upper coat with a chisel, and placing them upright close together, he executed his business so effectually, that the very first day he did as much as fifteen of his men could have done, and passed his plane over all the stones in the line, whereas in the common way they must have been done singly, by which means the work was much more true, though performed only with the joiner's old tools. This astonished even the person who performed it, but at the same time it encouraged him to think of adding to the invention, and in a short time he carried it much further than the author expected.

In order to this, he contrived a new sort of planes, in which the wood and iron were so disposed, that he was able to execute a cornice, or entablement, in which were three, four, or five mouldings of different forms and sizes, at one operation, and by these means performed with his own hands as much, in the same space of time, as could have

been done, in the common method, by forty hands. The result of all this was, that the building being finished, upwards of fifty parts in sixty were taken off in the expence. The only difficulty that was met with, at least worthy mentioning, arose from flints being found in the stones, which they were obliged to remove; but this, it seems, was no new inconveniency, but is experienced also in the common way, and when the work is done with a chisel; neither is it impossible, when this new invention shall be farther improved, that even this single difficulty may be got over.

[We are apt to think highly of foreign inventions; and accordingly this of stone-planes is cried up. But the like was done some years ago in England. Mr. Sowerby, a gentleman near Penrith, in Cumberland, had a table made of slate, (which is much harder than free-stone,) with mouldings on the sides regularly performed by a joiner with his planes.]

1748, Jan.

IV. Wonderful Memory of William Lyon.

WILLIAM LYON, a strolling player, who performed at the theatre in Edinburgh, and who was excellent in the part of Gibby, the Highlander, gave a surprising instance of memory. One evening over his bottle, he wagered a crown bowl of punch, a liquor of which he was very fond, that next morning at the rehearsal he would repeat a Daily Advertiser from beginning to end. At the rehearsal his opponent reminded him of his wager, imagining, as he was drunk the night before, that he must certainly have forgot it, and rallied him on his ridiculous bragging of his memory. Lyon pulled out the paper, desired him to look at it and be judge himself whether he did or did not win his wager. Notwithstanding the want of connection between the paragraphs, the variety of advertisements, and the general chaos which goes to the composition of any newspaper, he repeated it from beginning to end, without the least hesitation or mistake. I know this to be true, and believe the

parallel cannot be produced in any age or nation. Lyon died about four years ago at Edinburgh, where he had played with great success.

[We heard of this performance many years since, when the Daily Advertiser, though larger than other papers, was not so large and crowded as it has been of late. It is said, that the late Mr. Heidegger could name all the signs from the Exchange to St. James's, on one side the street, after once walking to observe them.]

1752, Sept.

V. Method of increasing the Solidity, Strength, and Duration of

Timber.

A new Method of increasing the Solidity, Strength, and Duration of Timber. By M. de Buffon, of the Royal Academy of Sciences at Paris.

To

answer these purposes nothing more is necessary than to bark the tree from top to bottom, in the sap season, and to suffer it to become quite dry before it is felled, which may be done at a trifling expence. Vitruvius and Mr. Evelyn have indeed just mentioned this method, but I believe nobody before me has thoroughly considered it.

In the beginning of May I caused four oaks of about 30 or 40 feet high, and about 5 or 6 feet in girt, to be barked standing; all of them were in full vigour, high in sap, and about 70 years old. I ordered the bark to be stripped off from the top of the body to the foot: this is an easy operation, for in the sap season the bark parts without any difficulty from the body. These oaks were of the kind, common enough in forests, which bear the large acorns. When they were quite stripped of their bark, I caused four other oaks of the same kind, which grew in the same soil, and as like them as possible, to be felled. My intent was to have barked six, and to have felled as many on the same day; but this could not be accomplished before the next day of these six barked oaks, two happened to be considerably less in sap, than the other four. I caused the six felled trees to be brought and laid under a shed, there to dry in their bark till I should have occasion to compare them with those which had been barked. I fancied that this operation must affect them in an extraordinary manner, and produce

considerable alteration in them. I visited my barked trees very carefully during two months, but could perceive no great change. On the 10th of July, however, one of them 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

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.