same princiThe immense

permost, can then have a communication with the colder water beneath-this is the blunder; for the heated water being in contact with the colder water beneath, will be gradually deprived of its caloric, until both become of the same temperature, and precisely on the ple that cooling goes on. depth of Loch Ness in the bowels of the earth, at least 2500 feet below the level of the sea, and the temperature of the earth being about 50 deg. Fahrenheit, is, undoubtedly, the source from which the waters of Loch Ness keep such an equable temperature, any heating, or cooling, on its surface amounting almost to nothing; and there is not the least indication, either by the smell, or the taste, that the waters of Loch Ness are affected by pyritical strata. This doctrine was taught by the late Professor Anderson, thirty years ago.

I am, Sir,

Your most obedient servant.

J. P. SIR,-The cause of Loch Ness not being frozen is correctly stated by J. P. to be owing to its extraordinary depth; for the objections thrown out by G. must vanish, when we consider that the stratum exposed to the action of the atmosphere, is so small, compared to the great body of the Loch, that long before it can sink to the bottom, the caloric it had lost at the surface is restored by the warmer mass below, and its descent arrested. And though this appears to reduce the temperature of the whole mass, yet that is not the case, for it must be recollected, that the severest frost never penetrated beyond the depth of a few feet into the earth, which is again melted in a short time; and as caloric always tends to an equilibrium, what is lost by the water is immediately supplied by the land; thus, it will be found that all deep lakes continue, at a certain depth, of a uniform temperature throughout the year. Should the explanation I have endeavoured to give of this fact, be unsatisfactory to your readers, by consulting Dr. Ure's Dictionary, article" Climate," I doubt not they will be convinced. I am, Sir,

ON THE CHEAP BAROMETER.

Near Glasgow, 3d Feb. 1824.

SIR, I suspended three of the barometers, described in No. IV. of your Magazine, on little frames, with a platform under their mouth, to show if a drop fell from them. They were placed in different situations, two in a dwelling house, with no fire in the apartments, and one in a work-shop; the lower surface of the water, in each, assumed various degrees of convexity and concavity, but they were seldom all alike; one would have been convex, another concave, and a third even with the neck of the phial, at the same time.

I looked, in vain, during the space of eight or nine months, for a drop of water falling from any of them, and yet the water disappeared. What, then, became of the water-and how got air into the phial? The water was evaporated slowly from its lower surface, until it assumed a pretty lengthened concave figure. When the vacuum was thus increased in the phial, above the water, the sides of the cone then came together, and inclosed a bubble of air, which ascended through the water, supplied the vacuum with air, and the water instantly assumed a convex figure below; I happened to observe this process, after long watching. Now, here two extremes in the figure of the lower surface of the water took place, in the twinkling of an eye, from arid drought to rain, or its close approach, according to D. M.'s probatum est.

I must acknowledge, however, that to my weak capacity, it showed a total absence of the properties of a barometer, but a fine specimen of the means which Nature employs to keep peace in her family.

As it is by mere chance that one can see the above process going on, an expement which I made to-day, with the enclosed phial, (although it has rather a wide neck,) will give a good idea of it. Fill the phial only half-full of water, for the more air there is in the phial, the experiment will be quicker; invert it, and hold it steadily in the hand. The heat of the hand will expand the air within the phial, and allow a drop or two of water to fall; hang it up in a cool place, and a concave surface will soon be formed below, and extend, till a bubble of air be inclosed, and ascend through the water, as before noticed.

The necessity for cutting off the rim

of the phial, arises, I apprehend, from another cause than that assigned by Y., in No. V. Phials have a smooth, and, generally, a sort of bell-mouth; this furnishes a sort of inclined plane for the water to steal away, as it were, from the action of the atmosphere. It appears to

be the sharp areas produced by cutting off the rim which is the turning point in the case.

You will see that the fracture

of the phial I have sent, is far from being even, or at right angles with the body of the phial, which is what I understand Y. to mean by a perfectly level surface; and though the neck is wide in proportion to the phial, it carried water many months.

Wishing you every success in your undertaking,

I am, &c.

A MECHANIC.

Answers to W. G.'s Queries, by a Glasgow Mechanic.

1. ON NEAR-SIGHTEDNESS.

In all persons that are extremely fair-haired, and white-skinned, there is either a deficiency in the quantity, or a derangement in the quality; or, (speaking technically,) a morbid secretion of the colouring matter of the skin, and of the black pigment (Pigmentum Nigrum) of the eye, a black or darkish looking substance, that completely overspreads that delicate expansion of the optic nerve, the retina, and acts as a shade to it, and prevents the too strong action of the rays of light from deranging its fine organisation.

If this Pigmentum Nigrum is either deficient in quantity, or too transparent in its nature, to act as a proper and sufficient shade, there will, in such cases, be a proportionate contraction of the pupils, in order to prevent too strong a glare of light striking upon the retina, and in proportion as the pupil is contracted, the distance of vision will be lessened.

It is from this cause that the Albinos, or Leuco-Ethiopians, take their strange peculiarity. In their case, there is probably a total want of the Pigmentum Nigrum, and, from the exceeding vascularity of the iris, in the completely transparent eye, the peculiar red appearance arises.

The colour of the eyes of white rabbits, white mice, owls, sparrows, &c.,

arises from the same causes; and, if a person will look clearly into the eyes of one of these animals, he will distinctly see the manner in which the objects are inverted.

2. ON LAUDANUM.

The first, and most effectual means of counteracting the effects of laudanum, is the emptying of the stomach; for which purpose the patient should be made to swallow from fifteen grains to a scruple of Sulphate of Zinc, or from five to ten grains of Sulphate of Copper, dissolved in water; and the vomiting should be kept up for a considerable time, and urged by irritation of the fauses.

When vomiting cannot be properly produced, in consequence of the paralyzed state of the nervous system, the cold bath has been said to restore the energy of the brain, and thus to render the person susceptible of the stimulus of an Emetic. Blood-letting, under some circumstances, is highly extolled. When this is resorted to, the jugular vein is preferred, from the more immediate relief it gives to conjestion of the brain. Should these means fail, it has been proposed, by an eminent physician, M. Orfila, that one or two grains of Tartarized Antimony, dissolved in one or two ounces of water, should be injected into the veins.

It was formerly proposed, by Boerhaave, to empty the stomach of its poisonous contents by means of a syringe; which operation, we see, has been successfully tried by Sir Astley Cooper, in his late Surgical Lectures. Vinegar, and vegetable acids, were long considered an antidote to opium; but the experiments of M. Orfila have clearly proved, that, so long as any portion of the opium is in the stomach, these, so far from doing good, considerably aggravate the symptoms produced by this Narcotic, in consequence of the power they possess of dissolving it.

When, however, the opium has been expelled by vomiting, these acid drinks have the property of diminishing the concretive symptoms. The powers of the habit should, at the same time, be supported by brandy, strong coffee, and cordials, and the sufferer, should, if possible, be kept awake, and in a gentle motion. Dr. Currie recommends that warm water, at 106 or 108 degrees, should be poured on the person to remove the stupor.

SIR, It would oblige a mechanic, if any of your Correspondents would give the cost of a five, ten, or twenty-horse steam power, house and machinery.And, what it will cost to keep it in working order, for a term of five, ten, or twenty years.

If it comes within the range of any one of your Correspondents' knowledge, he would oblige me by stating the cost of a water-power of five, ten, or twenty horse power; with tear and wear for a period of five, ten, or twenty years, including the expense of the dam and lade. It would also be a favour to inform the writer hereof, the real weight of a steam-power of five, ten, or twenty horse power, including the boiler.

I am, Sir, Your's truly,

QUERIES, &c.

Edinburgh, 4th Feb. 1824. 1. When the dark part of the new moon is faintly visible, or, (as the saying is,) when the old moon is seen in the new moon's arms-why do we augur bad weather? and, What is the cause of this phenomenon?-J.

2. Is there any method of rendering a bladder permanently soft and pliant, like chamois skin, or worn linen, without destroying its property of holding such fluids or gases as it does in its natural, or dry state?-What is the process, and what animal's bladder is best suited for it?-G. M.

3. Mm. wishes to know the manner of exhibiting some natural movements of figures to be seen through a magic lan

tern.

Results of some experiments lately made with a Magnetimeter, or new instrument for measuring the magnetic attraction, and dip, or inclination of the needle. -BY J. SCORESBY, Jun. F. R. S. E. &c.

1.-Iron bars become magnetic by position, excepting when placed in the plane of the magnetic equator; the upper end as regards the position of the magnetic equator, becoming a south pole, and the lower, a north pole.

2. No attraction, or repulsion, appears between a magnetised needle and iron bars; the latter being free from permanent magnetism whenever the iron is in the plane of the magnetic equa

tor; consequently, by measuring the angle of no-attraction, in a bar placed north and south, we discover the magnetic dip.

3.- Before a magnet can attract iron that is totally free from both permanent and positionary magnetism, it infuses into the iron a magnetism of contrary polarity to that of the attracting pole.

4.-A bar of soft iron, held in any position except in the plane of the magnetic equator, may be rendered magneti→ cal by a blow with a hammer, or other hard substance; in such cases, the magnetism of position seems to be fixed in it, so as to give it a permanent polarity.

5. An iron bar, with permanent polarity, when placed any where in the