communicated a shock to every person he touched with the other, whether such person were in contact with the boiler, or merely standing on the brickwork which supported it; but that a person touching the boiler received a much stronger shock than one who merely stood on the bricks." Mr. Armstrong made some further experiments, all of them tending to confirm his first observations; but, being unable to account for these appearances, he committed their results to Dr. Faraday. This gentleman suggested a number of experiments to Mr. Armstrong; and, in his remarks on the nature and origin of electricity discovered to exist in steam, says, "The evolution of electrictity by evaporation described by Mr. Armstrong is, most likely, the same as that already known to philosophers, but on a much smaller scale, and about which there are, as yet, doubts whether it is to be referred to mere evaporation, as Harris says, or to chemical action, according to others. This point neither settles nor illustrates; but it gives us the evolution of electricity during the conversion of water into vapour upon an enormous scale, and, therefore, brings us much nearer to the electric phenomena of volcanos, waterspouts, and thunderstorms than before." The electricity alluded to by Dr. Faraday as being already known to philosophers has, in reality, as much relation to the electricity proceeding from the conversion of steam into water, as light has to darkness, inasmuch as the negative state was already known, or, more properly, suspected, when water was being converted into steam, but the positive electricity discovered on this occasion was never before detected under the same circumstances.

Positive electricity is the only electricity, negative electricity being the appellation given to a state of things where it does not exist, or just as we speak of cold as being the opposite of heat.

The proofs we have of the existence of that peculiar state of things termed negative electricity, in connection with evaporation, are illustrated in the following simple experiment:-Adjust a platinum crucible, containing a little water, on the brass ball or plate disc of a common gold leaf electrometer, then add a red hot cinder to the water contained in the crucible, which will cause evaporation to take place, and, at the same time, the gold leaves will be distended towards the sides of the instrument. This action of the leaves points out to us that when water is being converted into steam, in other words, evaporated, that electricity is absorbed. Not only is electricity absorbed during the progress of evaporation, but I am led to infer further, that it is essential to the process itself. Since this paper was read in Liverpool, a paper has been published in the Philosophical Magazine detailing an experiment which goes very far to prove this. The writer, Mr. Rowell, took two cups of water, each containing eight ounces. One of them was made to communicate with the earth by means of a copper wire: the other was what electricians term insulated, having no metallic communication with the earth. They were both placed in otherwise equal circum

stances in a warm room over an oven. In twenty-five hours the cup, having electrical communication with the earth, had evaporated fourteen dwt. and nine grains more than the one having no communication. I have repeated a similiar set of experiments, and with nearly similar results, always, at least, showing an excess in favour of non-isulated vessels of water. I may here state that the writer, in the same communication, briefly says, he has entertained views somewhat similiar to some of those I have published in the foregone sections, and that he has entertained them since 1840. As he will, in all probability, publish them in detail, at present I can only say my own views on the same subject were far from being matured until a later period.

In the paragraph above quoted from Dr. Faraday, it is also worthy of remark, that he at once seemed to perceive the necessary connection that existed between the electricity given out by the steam and the electrical phenomena of the heavens.

In the first experiments made by Mr. Armstrong, he was led to imagine, that, if electricity was given out with the steam at a small aperture of the boiler, it would, in all probability, exist in much larger quantity in the interior. Of course, with the views I have explained, namely, that its existence in the free state was caused by the conversion of the steam into water, it was not difficult to foresee, that any experiments to prove this would fail. This gentleman, however, made a series of experiments with this view, but no electricity could be elicited in the steam, while it was steam, but only when it had become water was this force perceptible.

From the results of these experiments, it is scarcely possible not to view them as principles that may not prove unimportant in the great business of life, but more particularly with reference to the economy of steam-engines. We thus see evaporation, or the formation of steam promoted by metallic conducting substances, on the one hand, and, when about to be condensed, on the other; there can be little doubt that a like conducting substance to carry off the electricity generated during the process would also facilitate it. I have no means of making such an experiment on the proper scale; but, where even a small saving of fuel might be the result, it is worthy of consideration, and I should be but glad to hear of such experiments being made.

The

With respect to the application of these results to the electrical phenomena of the atmosphere, I trust they are, by this time obvious. Still, I may be permitted to repeat, that the air, at all times, contains a very large proportion of steam, invisible to the eye, and, hence, termed transparent aqueous vapour. From the water contained in this steam is formed cloud, rain, hail, and snow. accidental result observed in the steam-boiler, at Newcastle, shows us clearly, that, when steam is condensed, it gives out electricity. Cloud, then, is admitted on all hands to be the condensed steam of the atmosphere. I now ask, will it not give out electricity? or, I may add, is this phenomenon to be peculiar to the immediate sur

face? or is it not far more likely to be collected in greater quantity in high altitudes, where the process of cloud-forming goes on unconnected with any conducting substances, where it is, in fact, insulated?

This granted, there remains not the smallest difficulty in accounting for the hitherto mysterious origin of electricity in the atmosphere. When we look at the immense amount of evaporation going on at all times on aqueous surfaces, and the corresponding amount of condensation going on in the atmosphere, it is, at first sight, only wonderful that the resultant electricity does not play a more conspicuous part than it really does. The observing inhabitant of a tropical climate will have much less difficulty in giving his assent to these views than he of a colder or more temperate one.

There are many facts and observatious that might be adduced of the essentially electric nature of cloud, which, from the nature of the medium in which these papers have been published, are, necessarily, omitted; but I may mention, that luminous falls of snow have been observed from time to time. Those are perfectly explainable on the principles published in these papers. The most notable was observed by the Rev. Colin Campbell, and published in the first series of the Edinburgh Philosophical Journal. I may also mention that, when relating my views on atmospheric electrical phenomena, some months ago, to a celebrated professor of astronomy, he informed me, that, while observing the movements of the heavenly bodies on clear, star-light nights, it sometimes happens that a cloud will form often obstructing the field of view. Under those circumstances, he has been able to note the time, by his chronometer, with the naked eye, which, while there was no cloud visibly existing, he was unable to do. Such an occurrence is perfectly explainable, if we suppose a mass of cloud each globule of which shall be surrounded by an atmosphere of electricity, there would be luminosity enough emitted to account for increased light.

I now close my observations on these subjects; and I may add, that I have endeavoured to use as few really technical terms in explaining my views as the subject would admit. I have used the medium of a newspaper to convey them, in the first instance, to the public; a mode of conveyance of scientific subjects generally sneered at by contributors to philosophical journals, as they affirm, that an appeal to usual newspaper readers is made to those least capable of judging on a scientific subject. There is some force in this, and, with me, would have had weight in more abstract science. But whatever relates to meteorology, I hold, cannot be too widely dif fused in a great maritime town like Liverpool, the subject now being admitted to be of immense importance, since the science has become more fixed, and less subject to quackery than it was a very few years ago.

If these papers should have the slightest effect in tending to increase the desire for meteorological observation in Liverpool, I should feel much gratification. Public meteorological observatories should be general throughout the empire; but in no place that we

Occasional

can name is the want more felt than in our own town. astronomic observations for navigation are practically useful; further than this, their practical utility is questionable. But, with meteorological science, every observation has a practical tendency, making us more completely acquainted with the changes that take place in the sea of atmosphere that surrounds our earth, and in which reside the elements of all those changes usually termed weather, good or bad, hot or cold, damp or dry; and, it may be justly added, on its changes depend the existence of much health or disease; prevalent epidemics being attributed, by many, and perhaps justly, to atmospheric causes.

POSTSCRIPT.-In the preceding papers a few errors have crept in, especially in section the fourth, where "caloric of electricity" occurs, it should be " of elasticity," also for "most elastic," respecting water, read "most inelastic."

In propounding these views, it will be observed I have altogether assumed the theory of Franklin respecting positive and negative electricity, believing, in point of fact, the latter to be a nonentity; but, where I make mention of negative bodies in relation to clouds, it is meant in relation only to cloud possessing a larger portion of the subtle agent.

LONDON ELECTRICAL SOCIETY.

ON Tuesday, July 21st, 1841, a paper was read by Andrew Crosse, Esq., the subject of which was "The Perforation of nonconducting substances by the mechanical action of the Electric Fluid."

The author states that about some twenty-two years ago, he found that if an intercepted current of electricity, from a common electrical machine, were passed between the points of two platinum wires, well screwed on a narrow slip of window glass, both wires being on the same side of the glass, and in the same straight line, the vicinal extremities about one tenth of an inch apart, and the remote extremities in connection with the positive and negative conductors respectively, and that if the strip of glass thus prepared were placed in a vessel of water, it would become perforated, by the sparks passing between the points of the wires, from about 200 or 300 revolutions of the machine. The perforation is cylindrical, and tolerably even from one side of the glass to the other, and at right angles to its plane. Another person who had repeated the experiment found the glass perforated beneath the point of the negative wire, and not directly between the two wires. This experimenter considered the perforation due to chemical, and not mechanical, action; resulting, as he thought, from a decomposition of the glass. Mr. Crosse afterwards repeated the experiment many times, and in every case the perforation was directly between the wires, and is perfectly satisfied that the effect is mechanical; and states that the most

powerful electrical machine would fail to produce a visible decomposed speck on glass however exposed to its action.

About two years ago Mr. Crosse's attention was again directed to this experiment, and was led to vary it in the following manner. The strip of window glass was four inches long, and half an inch broad; and to one side of it the platinum wires (one-thirtieth of an inch diameter) were secured by tying with waxed silk thread, having their vicinal extremites one-twelfth of an inch apart. The glass thus equipped was placed in an empty dish, with the wired side upwards, and the remote extremities of the wires connected with the prime and negative conductors, as before with the precaution of intercepting the current and forming it into distinct and powerful sparks, by placing one or two insulated brass balls at the positive end of the circuit. By this arrangement no effect was produced on the glass by one hundred revolutions of an eighteen-inch cylinder machine, in high working order, and capable of producing a fifteen-inch spark between two five-inch balls. 2nd. The dish in which the glass was placed, was next filled with water, covering the points of the wires to the height of an inch. Twenty-five revolutions of the machine produced a fracture in the glass, between the points of the wires. One hundred revolutions extended the fracture, and produced two small cracks which diverged from the positive to the negative side. Two hundred revolutions occasioned a small excavation between the wires, but on the opposite side of the glass; and by two hundred and fifty revolutions, the perforation was completed. 3rd. Another slip of window glass was prepared as in the last case, but the wires were only one-twentieth of an inch apart. A perfectly circular hole, without any crack, was made through the glass between the wires, by three hundred revolutions of the machine. The hole in this case, as in the last, was conical, being narrowest on that side on which the wires were placed. If the water barely covers the wires on the glass in experiments of this kind, it is projected upwards from between the wires to more than a foot high, playing like a fountain by the lateral force of the sparks. If the glass be inverted in the dish, having the wires on the lower surface, and the whole barely covered with water; the electric sparks, as they pass between the wires, displace minute pieces of glass from the upper surface of the slip, and a small jet of vitrious particles is kept playing upwards, as was the water in the former case. 4th. Two platinum wires were secured at one-twentieth of an inch apart by wax, to the bottom of the inner surface of a watch-glass and the latter filled with water; twenty revolutions of the machine perforated the glass, which first yielded on the outside. 5th. Two wires were fixed, as in the preceding cases, to the outside of a glass tumbler filled with water. No effect was produced by 100 revolutions. The wires' points were afterwards covered with wax, and 200 revolutions produced a slight abrasion of the glass between the wires, but