Графични страници
PDF файл
ePub

My friend and relative, Joseph T. Price, of Neath, Glamorganshire, has furnished me with the results of some observations made last spring, in three collieries in the neighbourhood of that place. The thermometer was buried for many hours from one to two feet under the ground, at the bottom of each of these collieries in one of them, which was only 10 fathoms deep, the mercury stood at 50°; in another, 36 fathoms deep, it stood at 58°; and in the third, which was 90 fathoms deep, it stood at 62°. The difference between the first and last mentioned collieries was 12°, which ratio nearly corresponds with that obtained in our mines.

:

It has been surmised that the heat noticed in the mines may be attributed to the presence of metallic, and other inflammable substances; but when all the facts are considered, no causes, merely local, can be imagined capable of producing such constant, extensive, and powerful effects. If the water received its heat from the metallic veins, while passing through them, it would surely become strongly impregnated with mineral substances; this is not, however, the case. I analyzed some from the deepest part of Dolcoath, taken at 82°, immediately from the copper vein, and obtained from a quarter of a pint of it only half a grain of residuum, consisting of sulphuric acid, some oxide of iron, and a little lime. I found a greater proportion of the same substances in some water from a cross level, at a distance from any vein, 200 fathoms deep, in the same mine.

Water from the bottom of the United Mines, of the temperature of 82°, contained six grains of muriate of lime in a quarter of a pint. Some water taken from the deepest parts of Treskerby and Ting-tang, was, from the former mine, very slightly impregnated with sulphate of iron, and had a trace of muriatic acid; and that from the latter mine contained a very minute portion of the muriate of lime.

Since my last communication on the subject of the temperature of mines, I have had a thermometer, four feet long, placed in a hole three feet deep, in a copper vein, at the end of the deepest level, or gallery, in Dolcoath, which is 230 fathoms, or 1380 feet, under the surface; a spot where no workmen were employed, and where the current of air must have been small. The hole was filled with clay round the stem of the thermometer, so as to prevent the circulation of air near the bulb, and in this situation it remained more than eight months. It was often examined during that period, and was always found to indicate a temperature of 75°, or 750, unless it had been recently overflowed by water. This happened several times, in consequence of accidents to the machinery of the mine, and more than once, the water filled the level for some weeks. As soon as it had subsided, so as to permit access to the thermometer, the quicksilver was observed to have risen to 77°, but in two or three days it again fell to 7510.

Table of the Temperatures of sundry Mines at différent Depths as taken in or near the Veins.

[blocks in formation]

NB. The capital letters denote the rocks which inclose the veins, viz. G. Granite, S. Schist, P. Porphyry. The small letters a. e. w. show that the tempera

ture is that of the air, earth, or water.

• Here there was a strong current of air.

III. The third and last paper we have to abbreviate is by Dr. J. Forbes, late Secretary of the Society (Trans. ii, 159-217).

1. Huel Neptune.-Copper mine, situated in killas. Height above the level of the sea, about 200 feet. Depth, at the period the observations were made, 550 feet. (Depth in 1822, 750 feet.) Number of men employed under ground 120. Expenditure of candles per month 1200 lbs. Expenditure of gunpowder ditto 250 lbs. Quantity of water discharged per day 216,000 gallons. Temperature of this at the adit at the time the observations were made 60°. (in 1822, 62°.) Has been working 11 years (1822).

2. Botallack.-Tin and copper mine. Height above the level of the sea about 40 feet. Depth at the time the observations were made, 570 feet. (Depth in May, 1822, 672 feet). Number of men employed underground 150. Expenditure of candles per month 1200 lbs. Expenditure of gunpowder ditto 600 lbs. Quantity of water discharged by the pump daily 57,600 gallons. Temperature of this at the adit in 1819, 62°, in 1822, 67. Has been worked 17 years (1822).

3. Little Bounds.-Tin mine. In killas and granite. Height above the level of the sea 72 feet. Adit at the sea-level. Depth from the surface 504 feet. Number of men employed under ground 25. Expenditure of candles per month 48 lbs. Expenditure of gunpowder ditto 60 lbs. Quantity of water discharged by the pumps daily 69,000 gallons. Temperature of this water 5510.

This mine has been worked 30 years, but very little has been done in it of late years, and the water has consequently risen in it, to the 40 fathom level under the adit, that is, to the height of 192 feet from the bottom: it is kept under at this level by the partial action of the engine.

4. Ding Dong.-Tin mine. In granite. Height above the sea level about 400 feet. Depth from the surface 606 feet. Number of men employed underground 120. Expenditure of candles per month 900 lbs. Expenditure of gunpowder ditto 300 lbs. Quantity of water discharged by the pumps daily 50,000 gallons. Temperature of this at the adit, 61°. Has been worked eight years.

5. Huel Vor.-Tin mine. In killas. Depth from the surface 948 feet. Number of men employed underground 548. Expenditure of candles per month 3000 lbs. Expenditure of gunpowder ditto 3500 lbs. Quantity of water discharged per day 1,692,660 gallons. Temperature of this at the adit 67°. Has been worked 12 years.

6. Dolcoath.-Copper mine. In killas. Height above the level of the sea about 300 feet. Depth from the surface in 1819, 1386 feet; in 1822, 1428 feet. Number of men employed underground (1822) 800. Expenditure of candles per month 6000 lbs, Expenditure of gunpowder ditto 2600 lbs. Quantity of water discharged by the pumps daily 535,173 gallons. Temperature

of pump water at the adit (1822), in the eastern part of the mine, 72°; in the western ditto (much shallower) 64°. Has been worked 20 years.

Mean Results of the Temperature of Six Mines.

[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][subsumed][merged small][subsumed][merged small][subsumed][merged small][subsumed][merged small][subsumed][subsumed][merged small][subsumed][merged small][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][merged small][subsumed][subsumed][merged small][subsumed][ocr errors][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small]

On the Occurrence of Cleavelandite in certain British Rocks. By W. Phillips, FLS. MGS. &c.

SOME specimens of the rock of Mount Sorrel, in Leicestershire, lately brought from that place by my friend S. L. Kent, MGS. and myself, appear to be chiefly constituted of two varieties of felspar, common, and glassy. A third variety in other specimens is reddish or red, sometimes extremely red, and nearly opaque. These appeared to us to be only varieties of the same mineral, and believing that mineral to be felspar, we should so have designated the whole in a communication which we purpose shortly to send for insertion in the Annals, on the rocks in question, and on those of Charnwood Forest, but for the remarks of M. Levy in the number for November, showing that much which had been considered as felspar is in fact cleavelandite.

"Here there was a strong current of air.

Felspar and cleavelandite, it is remarkable, agree in their earthy ingredients, which exist very nearly in the same proportions in both substances; but they differ in this, that the 13 or 14 per cent. of potash in felspar is substituted by about 10 per cent. of soda in the cleavelandite, which, moreover, is not so hard as felspar. These minerals possess natural joints parallel to the planes of the doubly oblique prisms, which are considered to be the primary forms of the two minerals; but these forms differ so completely in the measurements of all their angles, that there is no hazard of mistaking the one for the other, after submitting them to the reflective goniometer. This, in consequence of M. Levy's paper, we have done, separately, and with eare, and we find that in the Mount Sorrel rock, felspar and cleavelandite are intermixed; but it is impossible for us even to guess their proportions as ingredients, since for the most part it is difficult, frequently impossible, to separate them by the eye. It may, however, be observed, that the felspar is frequently translucent or transparent, and often reddish; the cleavelandite, white or yellowish-white, and nearly opaque, or various shades of red, and that the very red veins traversing the rock here and there, are chiefly of this mineral. Abundance of coinciding measurements on fragments of both substances satisfy us of their aggregation in this rock.

I have since sought for the cleavelandite in other rocks, and have found it, as well as felspar, in a beautiful porphyry from Glen Tilt; the specimen was obligingly presented to me some years ago by Dr. Mac Culloch. In this specimen it is both transparent and colourless, and red and opaque. I have also detected it in a porphyritic granite from Carnbrae in Cornwall: in this specimen it is translucent and colourless, and white and opaque, and felspar is more abundant in it. In the granite of Shap, in Westmoreland, there is an intermixture of a whitish or yellowish-white substance, of which some very minute and dull fragments have afforded measurements within one degree of those of the cleavelandite; and I do not hesitate to believe that. better specimens would prove it to be that mineral.

ARTICLE XIII.

On some Thermomagnetic Experiments. By Dr. T. S. Traill. (To the Editor of the Annals of Philosophy.)

DEAR SIR,

Liverpool Royal Institution, Nov. 21, 1823.

HAVING been lately engaged in some thermomagnetic expe riments, I have met with results which none of the papers New Series, VOL. VI.

2 G

« ПредишнаНапред »