it may not be unacceptable to have an account of the pits of it, and whatever else relates to it, taken on the spot.

This earth itself is a coarse harsh loam, composed of a very large shining sand, of extreme hardness, and a fine soft tenacious clay its value is its remarkable quality of standing the force of the most violent fires without running to a glass; which makes it extremely useful to all who have occasion for such fires, and is the reason of its being sent not only into all parts of England, but to Holland, Germany, and many other parts of the world. It is used for making the bricks. employed in building the wind-furnaces for melting iron, for coating over the insides of assay furnaces, used by the workers on metals, and on many occasions of like kind at the glass-houses, both in England and other nations.

The place where it is dug is Hedgerley, a small village about 22 miles from London, surrounded with hills, under one of which this loam lies. The pits are about a quarter of a mile south-west from the town, and 5 miles north of Windsor: they extend over 4 acres of ground, situated on the descent of a hill; and were intended to have been carried over much more ground by the person who now works them; but on trials the loam is found not to extend as was imagined. They dig, before they come at this, a very good common brick-clay, a tileclay, and a potter's earth, a kind of clay of a firmer texture, and deeper colour, than either of those; but the strata of these are seldom pure or regular, and at the boundaries of the stratum of loam a pure hard sand, evidently the same with that in the composition of the loam, but left loose, from there not having been clay in the way to bring it into the condition of the perfect mass. They have already worked the stratum so far as to find it bounded east and west by beds of this sand, and northward by chalk, and are therefore afraid it will be soon exhausted; at least, whatever they get hereafter must be procured with more labour and expence, as they have no where to search for it but higher up in the hill; from whence it must be fetched at greater depths, and much more expence; and this increasing difficulty of procuring it has been the reason of its. rising in its price to that it is now sold at, which is 5 shillings a bushel in London; but which is not to be wondered at, since on the spot the quantity that makes a thousand bricks, which used to cost 1s. 8d. now costs 10s. the digging, and will every year cost more and more, unless a new stratum of it should be discovered somewhere thereabouts, which their many unsuccessful trials make them at present despair of.

It is to be observed, that this valuable earth forms but a single stratum, and that does not rise and dip with the elevation and descent of the hill, as the strata of the earth, stone, &c. in hills usually do, but seems to be even and flat at its bottom; for the higher up the hill they open their pits, the deeper in propor tion they find the stratum of loam lie,

It is worthy observation, that this hill appears from this not to have been formed as the hills and mountains on the earth in general have been, by a disruption and elevation of the strata by violence from within the earth; for in that case this stratum of loam must have been elevated with them, and would have been as near the surface, or nearly so, in one part of the hill as in another, and need have been dug for no deeper from the top than from any other part; whereas, on the contrary, it appears to lie flat and level underneath the whole mass of earth, which makes the hill, and was probably the surface, on the first settling of the terrestrial and other matter from among the waters of the deluge.

The earth, which makes the hill, seems to have been a prodigious mass of matter, rolled along by the irresistible force of that immense body of water, and afterwards lodged upon it.

That this might be the case, the immense force of that vast quantity of water, and the ease with which heavy bodies are moved in water, may serve to makeprobable; and what the more favours the conjecture is, that the earth which makes the hill is not disposed in such regular pure strata, as the earths settled regularly from the waters always are, but seems evidently a mixed mass, made by the jumbling together of various kinds of clay, &c. which are in some parts of it found pure, though not in whole strata; and in others irregularly blended in different proportions one with another; which, as the principal matters that compose it are of very different colours, viz. a red and a white clay, is the more apparent. And this is further confirmed by there being none of those common extraneous nodules found lodged in it, which are so frequent in the strata of clay formed by subsidence; such as the ludus Helmontii, pyritæ, &c. These have settled with, and lodged themselves almost every where among those strata; but it is no wonder there are none of them here, if this hill has been formed as above; since in the rolling it along, they must naturally have been left behind: and he supposes that the frequency of these bodies in almost all our little claypits, and the entire absence of them in the vast quantities of clay that have been dug here, will be esteemed, by all who have looked deeply into these studies, one great argument of the truth of this system; which may also extend perhaps to many other hills as well as this.

As the workmen are now obliged to dig this loam at 26 feet deep, instead of about 14, at which depth they long found it, and must hereafter, as they are obliged to ascend the hill, dig it at 38 or 40 feet, the price of it will probably deprive us of it before the vein is exhausted.

It would be a matter worthy consideration, whether, from examining the parts it is composed of, a succedaneum might not be found for it, by an artificial mixture of similar substances. In order to attempt this, Mr. H., by means of water, disunited its parts, and procured them separate; and on comparing them

with the various earths and sands from different parts of England, which he at times procured, he thinks that he can exactly match the sand with one from Hampstead heath, and the clay with one from a pit near the lower end of Highgate the proportions may be easily learned, by accurate observation of the quantities of each, where disunited; and a succedaneum on these principles easily made.

It is evident, that the only reason why it endures the fire so much better than other clays, is the extreme hardness and great quantity of the sand it contains: and as he imagines it easy to throw a sand of equal hardness, and in equal quantity, into an artificial loam, he sees no reason to doubt of making it equally useful.

On the Relief found in the Stone from the Use of Alicant Soap and Lime-Water. By Mr. Rob. Lucas. N° 483, p. 463.

Dr. Morgan advised Mr. L. to drink a pint of lime-water every day. Colonel Morgan and his lady advised him to take 4 pills of alicant soap morning and evening; on which he resolved to add the soap-pills to the use of the lime-water; only, instead of the quantity proposed, he took between 20 and 30 a day, amounting to near an ounce; which he thought he might safely do, well knowing that Mrs. Stephens's prescription amounted to almost 3 oz. of soap, besides other ingredients.

He used with great success stone-lime newly calcined; but by those experiments it should seem, that the dissolving power of lime water made of oystershells, is almost double to that of lime-stone. There are two good qualities attending these remedies: the first is, that they are cheap, easily come at, and prepared by one's self. 2dly, that they may be safely used for a long time, without danger to health; for a quart of lime-water, and an oz. of soap, had never given him the least nausea, or lowness of spirits, or abatement of appetite, and he was never better in health than at the above date (1747).

His motive for being so particular in this affair, is a desire to be instrumental of giving ease to others in so unhappy a condition; being firmly persuaded, that what has already so far relieved him, will dissolve stones of greater magnitude than he supposes his to be.

On the Figures of some very Extraordinary Calculous Concretions formed in the Kidney of a Woman. By Mr. Charles Lucas at Dublin. N° 483, p. 465. These calculous concretions were formed in the left kidney of Mary Anne Mac Mahon, otherwise England, taken out after her death, in the 30th year of her age. They were of very irregular and various forms, mostly resembling many rough pebbles rudely united and cemented together.

On the Formation of Pebbles. By Mr. Wm. Arderon, F.R.S. N° 483, p: 467. In all strata of pebbles, that Mr. A. examined, there are some which are broken, and whose pieces lie together, or very near each other; but as bodies of such hardness could not be broken without some considerable force or violence, their situation implies that they suffered such force or violence as broke their parts asunder, in or near the place where they at present lie.

Others again have had pieces broken from them, though not the least fragment of those pieces can now be found: whence we must conclude, that whatever might be the cause of their fracture, they must either have been broken at some place distant from where they now lie, or the pieces broken from them must at some time or other have been removed to some distant place.

Several of these pieces of broken pebbles have their edges and corners so very sharp, that it seems as if they had never been removed from the place where they received the damage. Others have their sides and corners so blunted, rounded, and worn away, that one cannot help imagining they must have been very roughly tossed backwards and forwards against other hard bodies, and that too with great violence, or for a very long continuance; since without a great deal of friction such hard bodies could scarcely have been reduced to the forms they are now found in.

Among these strata of pebbles are several fragments of various kinds of marble, various kinds of sand-stone, and various kinds of gypsum, though this part of the kingdom affords no such thing; most of which have attained the hardness of the very hardest of our pebbles, as it should seem, by lying among them.

Such pebbles as are found here in strata near the surface of the earth, are much more brittle, and break easier without comparison, than those which lie in deeper strata for if the first of these fall, but with their own weight, on any other stone, from the height of 3 or 4 feet, they will break very frequently into ten or a dozen pieces; whereas such as are found deep in the earth will endure being thrown against each other with all the force one can give, and that too 20 times perhaps, before the least splinter of them can be broken off.

On the Distances between Asia and America. By Arthur Dobbs, Esq. of CastleDobbs in Ireland. N° 483, p. 471.

Professor Euler,* swayed by the opinion of captain Behring, seems still to believe that the last land he discovered is joined to California, which country is now known to be part of the continent of America, and not an island; in which fact of its being continuous to California, Mr. D. differs still in opinion

* See Phil. Trans., No 482, or Vol, ix, p. 320 of these Abridgments.-Orig.

from him; for if that were a fact to be depended on, he would candidly own that there could be no passage from the north-west of Hudson's Bay to the western ocean of America, without sailing near 70° of longitude; the distance of the north-east cape of Asia from the north-west of Hudson's bay, in a parallel almost as far north as the polar circle, before the passage can be made to the Pacific Ocean; which might therefore be very reasonably called an impracticable passage, as it could not possibly be made in one summer, if at all.

Now Behring fixes his north-east cape 126° 7′ east longitude from Tobolski; and Tobolski is 86° east from Fero; so the cape is 212° 7′ east of Fero, or about 194° east from London. By captain Middleton's observation of Jupiter's satellite at Churchill river in Hudson's Bay, that river is 95° west from London; which, added to 194°, makes 289°; consequently the north-east cape of Asia is 71° distant from Churchill, to complete 360°; which, in the latitude of 65°, computing 8 leagues to a degree of longitude, of which 20 make a degree of latitude, the distance between that cape and Hudson's Bay would be 568 such leagues.

From the known longitude of the north cape of Japan in 40° lat., which is pretty exactly known, from the observations made by the jesuits at Peking, and is about 150° east from London, and from the best computed longitude of California in 40° north lat., it lies in 130° long. west from London, making together 280°, leaves 80° for the distance of California from Japan; allowing 17 leagues to a degree of longitude in 40° north lat., the distance would be about 1360 leagues by the same calculation California must be at least 7 or 800 such leagues from the north-east cape of Asia; so that in so great a space there may be very great countries or islands,* without supposing the new discovered country continuous to California, and might well allow of an open channel or sea, from 50 to 100 leagues wide, between the discovered coast and California.

By the account given to professor Euler, Behring sailed southwardly to the Isles of Japan, and from thence sailed eastwardly 50 German miles, about 250 English miles; which makes about 80 leagues, of 20 to a degree. At that distance from Japan he discovered land, which he coasted north-west; still approaching towards the north-east cape, without going ashore, till he came to the entrance of a great river; where sending his boats and men ashore, they never returned, being either lost, killed, or detained by the natives, which made his discovery incomplete; his ship being stranded, and he afterwards died in an uninhabited island.

As no latitudes nor longitudes are fixed by this account, he probably sailed

* The Japanese, in their maps of the world printed in Japan, have laid down in this very tract two islands as large as Ireland, with the names to them, as appears in that map bought by Dr. Kempfer in Japan in 1686; now in Sir Hans Sloane's museum.-Orig.