socket; but I certainly never saw external objects by this light.

Sir Charles Bell, in his work on the Hand, page 174, states, that an officer received a musket-ball through the bones of his face. He said he felt as if there had been a flash of lightning accompanied with a sound like shutting the door of St. Paul's.

Haller speaks of such cases as by no means uncommon, and quotes the names of several authors who have related similar ones.

PAGE 46, line 12.

While making some physiological experiments suggested by Galvani's then recent discovery of what was supposed to be animal electricity, the following fact attracted my notice, and strongly and permanently impressed on my attention the useful subserviency of water and friction for the preservation and restoration of health.

When a nerve, which for some time has been detached from surrounding parts, is either carefully wiped quite dry with a piece of fine muslin, or (lest this should be thought to injure its structure), suffered to remain suspended till its moisture has evaporated, no contractions can be excited in the muscles, to which it is distributed, by touching it alone with any two

metals in contact with each other. But, if it be again moistened with a few drops of water, contractions instantly take place; and, in this way, by alternately drying and moistening the nerve, contractions may, at pleasure, be alternately suspended and renewed for a considerable time.

One

M. Fontana, in the first volume of his work on poisons, mentions some facts, which may, to some, appear to give considerable countenance to this explanation. The microscopical eels found in dry and smutty wheat; the Seta equina or gordius of Linnæus; and the wheel polypus, all, when dry, become apparently dead, but again recover motion and life when moistened with water. of the latter was put, by M. Fontana, upon a bit of glass, and exposed, during a whole summer, to the noon-day sun. It became so dry, that it was like a piece of hardened glue. A few drops of water, however, did not fail to restore it to life. Another was, in this way, recovered after a similar exposure of a year and a half. Father Gumillo, a Jesuit, and the Indians of Peru, are quoted by the same author, on the authority of Bonguer, as speaking of "a large and venomous snake, which being dead and dried in the open air, or in the smoke of a chimney, has the property of coming again to life, on its being exposed, for some days, to the sun, in a stagnant and corrupted water."

But it would almost require the credulity of an Indian to credit the testimony of the Jesuit.

The men who work in the deep copper and tin mines of Cornwall, seldom retain sufficient health to enable them to continue their employment beyond the age of 40 or 45; while in the equally deep coal-pits of Durham (I was told) men are to be found who have retained their strength even to their 70th year. This difference appeared to me to be occasioned, not so much by any deleterious effluvia from the copper, as by the exhaustion produced by fasting too long in the mine, and then, after many toilsome hours in damp, confined, and impure air, having to climb a succession of ladders for nearly an hour, before they could reach the surface. To this cause, I think the difficulty of breathing (with which all above the

age

of 35 seemed to be more or less affected) must be attributed. I felt the pulse of three young men a few minutes after they had emerged from a mine. It was in all feeble and hurried, and their respiration was laborious. They were in a profuse perspiration, and appeared so exhausted as to require long repose, and wholesome food, to restore their strength and efficiency. But in this state, unwashed and unrefreshed by food, they had to walk long distances to their homes. The Durham pit-men, on the contrary, are lifted from

their work by a steam-engine, and are well washed before they feed or repose.

This most salutary preservative of health (washing) is forced upon even the most indisposed of the pit-men in coal-mines, by the coal-dust retained on the whole surface by the perspiration which the confined situation of their work has rendered profuse. By this effective application of water and rubbing, the skin is restored to that active and imbibing state in which alone it can aid the lungs in giving oxygen access to the blood.

Till means can be devised for sparing men the fatigue of climbing from the Cornish mines, much might be done towards the preservation of their health, if the precautions of tepid bathing, refreshment, and even half an hour's repose could be provided for them, either before they leave the premises of their employers, or immediately on their return to their homes.

PAGE 50, line 10.

I was surprised, says Dr. Darwin (Zoonomia, vol. i., p. 564), and agreeably amused by the following experiment:-"I covered a paper about four inches square with yellow, and with a pen filled with a blue colour wrote on the middle of it the word Banks, in capitals, and sitting with my back to the sun, fixed my eyes for a minute

exactly on the centre of the letter N, in the middle of the word. After closing my eyes, and shading them somewhat with my hand, the word (Banks) was distinctly seen in the spectrum in yellow letters on a blue field, and then, on opening my eyes, on a yellowish wall, at twenty feet distance, the magnified name of Banks appeared written on the wall in golden characters."

If we look intently on a window for a minute in a cloudy day, and then close our eyes with the hand, still continuing to look in the same direction, a spectrum of the window and its bars will be seen, with the light and dark parts reversed; for the bars in the spectrum will be light, and the panes of glass dark. Both my eyes are dim from incipient cataracts, and to me each bar appears as double-that is, with the distance of an inch or more between the real bar and a second much fainter. When I incline my head to either side, the fainter bar approaches the real, till they form one line-analogous to the appearance of a line seen under a rotating Iceland crystal.

Both these experiments succeed best early in the morning.

A proof that this spectrum is certainly in the body's, and not the mind's eye, is, that it gradually disappears, whatever effort we may make to retain it.