at the same time with the sphere containing it. This property would seem somewhat conformable to the opinion of Halley, who supposed the earth to contain a spherical magnet, which rotated within the shell that we inhabit. And, what is more fortunate to the analogy, it is proved by the experiments that when the electric currents are of the same kind from the equator to the poles of both nucleus and shell, they both rotate in the same direction. The rotation would likewise be as effectual, were the magnetic poles removed to some distance from the axis of motion.

Another hypothesis might be advanced to account for the rotatory motion of the earth, and which would not require the supposition of its being hollow; but only to be regarded as a grand natural magnet, possessing a capacity for conducting the electric fluid. The former of those properties is admitted by almost every writer on magnetics; and the latter, it is presumed, will be as readily conceded.

From the second experiment we see the magnet rotate on its axis by the influence of electric currents from its equator to its poles. Had the magnet been a sphere instead of a bar, it might have represented the earth or planet more perfectly; but its figure, it is presumed, can make no difference in the result of the experiment.

It is now well known that electricity can be excited by heat, and the success of thermo rotations in the manner that I obtain them would, if formed into a sphere, depend upon the difference of temperature between the equator and poles. This property is obviously analogous to the natural state of the earth; for the sun exerting his greatest influence a few degrees only on each side of the equator, the polar regions are constantly kept at a very low temperature; so much so, that every attempt yet made to explore them has been rendered abortive in consequence of a prevailing intensity of cold; whilst the equatorial parts, it is well known, are as constantly kept in the other extreme. That thunder and lightning are by far more prevalent in the torrid than in the friged zones, is a fact that cannot be denied ; and that this difference of electrical phænomena is principally caused by the superior action of the sun in those parts, appears more than probable. Hence it may be fairly concluded, that the action of the sun either partly or wholly governs the general electrical phænomena of nature; and, either by producing or exciting this wonderful agency in the equatorial regions, dispenses its influence from thence to the poles of the earth.

Another circumstance that would be something in favour of the hypothesis is, that a magnetic body free to move in any direction, (a sphere suspended in space, for instance,) and having currents of electricity passing over its surface to its poles, would not only rotate, but would likewise maintain its parallelism. This may be easily demonstrated upon the principles shewn in Professor Barlow's

"Magnetic Attractions," second edition, p. 249, under the head Electro-magnetism.

Let NZC'Z', fig. 4, represent the magnetic sphere. NS its poles. Likewise suppose ZC and Z'C, to proceed from the zinc and copper sides of two batteries of equal power. Then the electric force in that part of the magnet between Z and C, or in the northern Z hemisphere, will tend to carry the pole N towards N. And the electric force in the southern hemisphere between Z' and C' will at the same time have a like tendency to carry the same pole N towards N'. But the pole N being

4.

N-C

N

N

acted on by the two equal and contrary forces, can have no tendency to either of these points; therefore must of necessity remain in its original position.

That pole of the magnet which possesses the same kind of magnetism as the north magnetic pole of our globe, being now properly called north; when the zinc sides of the batteries are applied at the equator, the magnet rotates from west to east, or, in the same direction as the earth.

Having pointed out these particulars, most of which are facts deducible from experiment, there can appear no extreme improbability that most of the phænomena which are observed to obtain with the heavenly bodies in our system, are physically produced by the powerful agency of electricity. And experiments may, in my humble opinion, be instituted, that would satisfactorily exhibit the whole; for we have already seen that rotation and parallelism are producible by electro-magnetism; and the thermo experiments serve to prove that the influence of the sun may be sufficient to excite continual electricity. Hence magnetic bodies placed within its influence may not only rotate and keep their axes parallel, but probably may likewise obey every other observed astronomical law with regular mathematical precision.

I am, gentlemen,

Your most obedient servant,

Artillery Place, Woolwich, Aug., 1824.

(To be continued.)

WM. STURGEON.

NOTICES OF NEW BOOKS, &c.

The Eighth Annual Report of the Royal Cornwall Polytechnic Society. SIMPKIN and MARSHALL, London.

The volume before us is another indication of the advancing usefulness of this highly valuable Society, and of the great importance to the advancement of the arts, manufactures, &c. of this country,

which such fostering and stimulating institutions would lead to, were they established and similarly conducted in our busy manufacturing districts, where competition, at present, is so actively carried on with a view to undersell, by the production of deceptive rather than by really improved articles of manufacture; and where genius is suffered to pine, and even smother, in obscurity, for want of aid, or basely robbed of its treasures for want of protection.

The premiums, prizes, &c., awarded to successful candidates, at the eighth annual meeting of the Royal Cornwall Polytechnic Society, were as follow:-Fifteen premiums, in small sums, amounting to upwards of forty pounds; four silver medals; seventeen bronze medals, and about forty-six other prizes of various kinds. By these means the Society at this meeting has acknowledged the talents of, and conferred its honours upon, upwards of fourscore persons; who are thus stimulated to future exertions in the most laudable pursuits to which the human mind can be directed.

The contributions of papers, essays, descriptions of inventions, &c., that were read at the eighth annual meeting, are on the following subjects:

1st.-Observations in Illustration of the History and Statistics of the Pilchard Fishery. By JONATHAN COUCH, Esq. F.L.S.-This paper is mostly confined to a narration of certain purchases and sales of salt and pilchards, by "Richard Trevill, an eminent merchant in the reign of Queen Elizabeth;" which is, no doubt, interesting in the locality of the Pilchard Fisheries.

2.-Statistics of the Pilchard Fishery, for the years 1838 and 1839. By Mr. J. S. COURTENAY.

3. Comparative Longevity of Miners. By Mr. ROBERT BLEE, jun. -It appears, from this document, that the average age at which miners die is different in different mines. In the Gwennap mine the average age is 46; in the Illogan, 49; and in the Camborne, 54. The average deaths from mine accidents has been 17 per cent. for the three previous years.

4.-Statistics of the Falmouth Public Dispensary and Humane Society. This is a table of items, by LOVEL SQUIRE.

5.-On the Atmosphere of Mines. By M. P. MOYLE, Esq.-This is a valuable scientific document, being a detail of results of chemical analysis of the air in different mines. For the particulars of these experiments we must refer the reader to the work itself: it will be sufficient, in this place, to shew the centage of oxygen in different trials, and under different circumstances :

At WHEAL VOR.-A tin mine in slate. At 280 fathoms depth the per cent. of oxygen was 18·416; at 250 fathoms, oxygen 16.69 per cent.; at 230 fathoms, oxygen 17.282 per cent.; at 214 fathoms, oxygen 16.762 per cent.; at 36 fathoms, oxygen 14.76 per cent.

GREAT WORK. Tin and copper mine; granite. At 170 fathoms, oxygen 17.544 per cent.

BINNER DOWNS.-Copper mine. At 104 fathoms from surface,

oxygen 16.764 per cent.

CARN BREA.-Copper mine; granite.

At 105 fathoms, oxygen

16.693 per cent.; at 95 fathoms, oxygen 14.51 per cent.

TRESAVEAN.-Copper mine in granite. At 156 fathoms, oxygen

16.35 per cent.

WEAL ANN.-Tin mine in granite.

At 80 fathoms, oxygen

16.72 per cent.; at 100 fathoms, oxygen 18.22 per cent.

CONSOLS.-Slate. At the bottom levels (no depth given), oxygen 17.78 per cent; second sample of air, oxygen 18.42 per cent.

Mr. Moyle concludes with the following appropriate observation: "The superabundant quantity of nitrogen and carbonic acid above that of a pure atmosphere, clearly points to a source of great mischief to the animal economy; and when combined with the great deficiency of vital air, or oxygen, we cannot much wonder at finding the predominance of pulmonary affections amongst our miners."

6.-On Asphyxia. Condensed from a Communication by M. P. MOYLE, Esq. As this epitome may be interesting to many of our readers, we give it complete :

"Asphyxy may be defined to be suspended animation proceeding from a primary arrest of the respiratory actions, the other functions being thereby abolished.

"Asphyxy has been very generally viewed as proceeding from causes which act in various ways; and the opinions respecting their nature and mode of operation have been extremely deficient in precision and accuracy. According to the meaning of the term above, asphyxy can only occur in a direct or primary manner, and from causes which either exclude the air from the lungs, prevent its renewal, or abstract that constituent of it which is requisite to the respiratory functions.

Though submersion be the most frequent, it is by no means the only cause of apparent death worthy the inquiry of the physiologist; but the suspension of vital action from strangulation and noxious gases exhibits phenomena so nearly similar, and require a treatment so strictly congenial, that any enquiry into the nature of submersion only would be narrow and incomplete. I shall therefore attempt a short description of the phenomena of departing life from the foregoing causes; an investigation of the efficacy of the means of cure, sanctioned by experience; and lastly, draw up a few short directions, which might be generally adopted by all those who might first gain access to the unfortunate individual who may be the subject of asphyxy.

In

"The duration of life in cases of asphyxy is very different. general, the more slowly the abolition of the respiratory function takes place, as in drowning, the longer does the action of the heart continue, although feebly and slowly, even after respiration has ceased; and to this circumstance, as well as to the fluidity of the blood, which is long preserved, is owing the power we possess

of recalling the asphyxied to life; the more slowly the state of asphyxy supervenes, the longer the person retains the ability of being re-animated, and vice versa.

"A minute anatomical description of the heart and lungs, the theory of respiration, or the appearances on dissection, do not become necessary in the present communication. My principal object being to draw a more general and just consideration of the importance of possessing sufficient medical knowledge as to be capable of rendering immediate assistance of the proper description, by the timely and judicious application of which, the lives of many of our fellow creatures may be saved, I shall therefore, in the first instance, give a line of general treatment to be adopted, and conclude with a few brief remarks for the guidance of all classes of persons, and whereby they may act with full confidence of doing their best for the patient until the arrival of superior aid and judg

ment.

General Treatment.

"The indications which naturally suggest themselves from the consideration of the causes of asphyxy, their mode of operation, and the ultimate results which they produce, are, 1st, to remove the patient as soon as possible from the causes which occasioned the asphyxied state; and 2nd, to restore the function of respiration, and through it, the circulation.

"The restoration of the function of respiration is to be attempted by various means, calculated, in the first place, to dislodge the impure air contained in the lungs; secondly, to replace it with pure air; thirdly, to excite the remaining vitality of the nerves and muscles; and fourthly, to restore the circulation by means calculated to return the blood from the lungs to the left side of the heart. The simultaneous attainment, as far as may be, of these objects, is to be attempted by a judicious combination of means.

"The patient should be placed on his back, in the open air of a mild and somewhat warm temperature, with the chest, shoulders, and head slightly elevated. He should be stripped of his clothing, and enveloped in a warm blanket; pressure should be made upon the breast and abdomen, alternating with relaxation, in such a manner as to simulate the action of the chest in respiration, By this means the foul air will be thrown out of the lungs; and the restoration of the capacity of the thorax, upon the removal of the momentary pressure, by the elasticity of the costal cartilages, will draw fresh air into the lungs. It will sometimes be of service to apply a hand upon each side of the thorax below the arm-pits, and by gentle shocks endeavour to expel the vitiated air. Whilst this is being performed, bottles of warm water should be applied to the feet, under the knee joints, on the inside of the thighs, and under the arm-pits. Dry warmth is particularly beneficial when applied to the epigastric region. After having used pressure, so as to simulate respiration for a few moments, insufflation of the lungs