some curious observations on the filling up of the passages formerly dug out in the old mines. By the trickling down of moisture along the sides of these passages they gradually become narrower, and approach each other.*

Poland.

3. The most extensive salt mines known are those in Poland, not far from Salt mines in Cracovia, at a small town called Wilizka. There is an imperfect description of them in the Philosophical Transactions. According to that account, they are 1,200 feet deep; and about 1,000 miners are constantly employed in them. The horses kept under ground become speedily blind, in consequence of the sharpness of the salt; and the hoofs of one of them, who had been long in the mine, were as long again as usual.†

Salt had been prepared in Cheshire for many years by boiling down the salt In Cheshire. springs which are common in that country; but in 1670, a rock of salt was discovered, from which they expected to be able to manufacture the article with greater advantage.‡

Cornwall.

4. There is a pretty long paper, published in the Transactions for 1671, Tin mines in giving an account of the method of working the tin mines in Cornwall, and of preparing and smelting the ore, and obtaining the tin. As the terms used are all provincial words, peculiar to the Cornish miners, without any explanation, the paper is not very intelligible to ordinary readers. The publication of a dictionary, explaining all the words used by the miners in the different mining provinces of Great Britain, would be a work of considerable value, and would greatly facilitate the attempts that may be made to improve the state of our mines. Something of the kind indeed has been attempted with respect to Cornwall, but at a period when the science of mineralogy was not sufficiently advanced to admit of an explanation of every term.

5. It is very remarkable that diamonds, by far the most beautiful and most highly valued of all the precious stones, have hitherto been found only in the torrid zone, in India, and Brazil. The mines, as they are called, consist of nothing else than the alluvial soil, no doubt originally washed down from mountainous districts. In this soil, diamonds are found scattered very unequally; sometimes occuring in great abundance, sometimes very sparingly. In some places the stones are all small, never exceeding a few grains in weight; in other places they are occasionally found as heavy as nine ounces. Diamonds have never yet been observed in their original position; from which circumstance one would be apt to suppose that this repository must be some of the newest rocks; as these are the rocks which from their situation are most liable to be worn away. In the Philosophical Transactions there is a particular ac

* Phil. Trans. 1670. Vol. V. p. 1189. Phil. Trans. 1670. Vol. V. p. 2015.

† Phil. Trans. 1670. Vol. V. p. 1099.

§ Phil. Trans. 1671. Vol. VI. p. 2096. See also

a paper on the same subject by Merret, Phil. Trans. 1678. Vol. XII. p. 949.

Diamond mines in India.

Calaminc.

Mining terms.

count of the different places in India, on both sides of the Ganges, where diamonds occur, the manner of digging and washing the soil, and the colour of the different soils thus wrought. The paper was communicated to the Royal Society by the Earl Marshal of England. The description of the soil and rocks is so imperfect as to convey no information. But there is one curious particular mentioned, that deserves to be noticed; we mean, the mode pursued by the Indians to dig through rocks. They kindled a fire on the rock, and when it was very hot they poured water on it. By this means the rock cracked and split into shivers for a certain depth; these fragments were removed, the fire again kindled, and water poured upon the hot rock as before. Thus they proceeded till they reached the requisite depth.*

6. Calamine is an oxide of zinc, which has been employed from time immemorial in the making of brass. There is in the Transactions an account of the method followed by the miners in digging this ore out of the earth, and preparing it for sale. Calamine occurs frequently in beds, and seems, in some cases, to exist in great abundance. The Mendip hills, in Somersetshire, were famous for their calamine mines; though, I believe, the ore is now pretty much exhausted in that quarter. From the description given of the calamine mines in Somersetshire, by Mr. Pooley, it is plain that he considered the calamine as occuring in veins. It is always mixed with some galena or sulphuret of lead. It is dug out of the earth, and being broken into small pieces is exposed to the action of a current of water, which washes away the light earthy matter, and leaves the calamine. The whole is then thrown into deep wooden vessels full of water, and agitated for a considerable time. The galena sinks to the bottom, the calamine is deposited in the middle, and the earthy matter on the surface. The calamine, thus separated from its impurities, is ground to powder, and is then fit for sale.‡

7. Dr. Nichols, Professor of Anatomy in Oxford, seems to have examined the structure of metallic veins with more accuracy than any other British writer of the early part of the last century. He published some observations on the mines of Devonshire and Cornwall, which possess some value. He has given us an explanation of several of the Cornish words used by the miners, of which the following may serve as a specimen:

Load, a vein.

Living load, a vein containing metallic ore.

* Phil. Trans. 1677. Vol. XII. p. 907.

† Pooley. Phil. Trans. 1693. Vol. XVII. p. 672. The practice followed at present, in Somersetshire, differs in several particulars from the account given in the text; though the object in view, and even the means employed, are the very

same.

§ Phil. Trans. 1728. Vol. XXXV. p. 402 and 180.

Dead load, a vein destitute of ore.

Flooking, a cross vein of stone; or dyke, as called in the North of
England.

He has some observations on the crystals of tinstone, and on its specific gravity compared with that of tin, and on its colour, much more accurate than any to be met with in chemical books of the same period.

8. In the year 1751, there was a very rich copper mine wrought at the river Precipitation of copper by Arklow, in the county of Wicklow, in Ireland. From this mine there ran aro iron. stream of blue-coloured water, of so deleterious a nature as to destroy all the fish in the river Arklow. One of the workmen, leaving an iron shovel in this stream, found it some days after encrusted with copper. This induced Mr. Johnston, one of the proprietors of the mine, to make a set of experiments on the subject, from which he concluded, that the blue water contained an acid holding copper in solution, that iron had a stronger affinity for the acid than copper, that the consequence of this affinity was the precipitation of the copper, and the solution of the iron when pieces of that metal were put into the blue water. These ideas induced the miners to dig a great many pits for the reception of this water, and to put bars of iron into them. By this means they obtained a very great quantity of copper, much purer and more valuable than the copper which they obtained from the ore itself by smelting.*

9. The superiority of Swedish iron over that of other countries, for the Swedish iron making of steel, is well known. Hitherto the British steel makers have not been able to employ British iron in their processes; they have found it too brittle to bear cementation. Attempts are at present making by some very spirited steel makers at Sheffield; and, from the products already obtained, good hopes are entertained of ultimate success. This superiority of the Swedish iron depends upon the great purity of the ore from which the iron is smelted. One of the most remarkable of these mines, if the name can with propriety be applied to it, is Taberg, a mountain of considerable size, composed entirely of pure iron ore, and occurring in a large tract of sand over which it seems to have been deposited. This mountain has been wrought for nearly these three hundred years, and yet its size is scarcely diminished.†

CHAP. IV.

OF GEOGRAPHY AND TOPOGRAPHY.

We are sensible that the title of this chapter, as a branch of natural history, will appear objectionable to many persons. There can be no doubt, that the topics which we mean to comprehend under it might have easily been arranged under other branches of science. But if we had followed that plan, which we acknowledge to be the usual one, the different topics would have still occupied a place by themselves, so that nothing would have been gained for those sciences, under which they would have been placed. Thus for example, had we arranged the facts respecting the latitude and longitude of places, which we mean to give in this chapter, under the head of astronomy, they must still have continued as distinct from astronomy, strictly so called, as they do at present, and have constituted a section apart. The fact is, that the geographical position of all the different spots of the earth constitutes a very important part of the natural history of the earth, as the description of the manners and customs of dif ferent nations do of the natural history of man. We might therefore have placed the former under geognosy, and the latter under zoology. Buty upon the whole, it appeared better to place them under a particular department by themselves.

The papers relating to geography and topography, in the Philosophical Transactions, amount to 67, and contain several particulars of considerable importance. They may be arranged under four distinct heads, namely: 1. The latitudes and longitudes of different places as determined by astronomical observations. 2. The observations detailed in the Transactions on the construction of maps. 3. The papers on hydrology. 4. The papers on topography. Latitudes and 1. LATITUDES and longiTUDES OF PLACES. The following table exhibits a longitudes of view of the different latitudes and longitudes determined in the Philosophical places. Transactions:

(a) Bradley and Maskelyne. Phil. Trans. 1787. Vol. LXXVII, p. 151.

(b) By the occultation of the bull's eye by the moon, 1682. Phil. Collect. No. V. p. 124.

(«) Phil. Trans, 1690, Vol. XVII. p. 453.

(b) The Greeks made it 43o 5′, the Arabians 45'. The real latitude is 41° 1′ 24′′. Phil. Trans. 1685. Vol. XV. p. 1295. (c) Ibid. (d) Ibid. 1698. Vol. XX. p. 53 and 371. (e) Ibid. 1726. Vol. XXXIV. p. 85 and 92. (ƒ) From an observation of Pere Feuillée. Ibid. 1721. Vol. XXXII. p. 2. (g) He was sent out for the purpose by the Lords Commissioners of Trade and Plantations. Vol. LVIII. p. 46. (1) Phil. Trans. 1776. Vol. LVI. p. 182. (1) Phil. Trans. 1790. Vol. LXXX. p. 385.

(k) Ibid. p. 182.

Phil. Trans. 1768. (i) Ibid. 1779. Vol. LXIX. p. 163. (m) Phil, Trans, 1777, Vol. LXVIL p. 16o ̧