by a mixture of oxygen gas with it. The former particular we esteem to be of great importance, for cold being perhaps the most powerful agent in destroying life, it cannot be less necessary to communicate warmth to the interior, than by baths and other means, to the surface of the body. The Royal Humane Society will assuredly hasten to add this to their other means of recovery. We would advise Mr. Read to furnish with the apparatus, air tight bags, which being applied to the extremities, and the air exhausted by the same instrument, would tend to relieve congestion of blood in the head and other parts, and facilitate its circulation.

Among other interesting articles on the table, was a section of a nettle, discovered by Mr. Cunningham, the Australian traveller, at Morton Bay, north of Sydney, grow. ing 100 feet high, and having leaves (some of which were exhibited) at least 8 inches by 9 inches. It will create, therefore, the less surprise, when it is stated that the section was not less, by our estimation, than 18 inches in diameter. It was sent by Mr. Lambert. Mr. Hemming forwarded some photogenic drawings, with the engravings from which they were copied; but neither these specimens, nor those exhibited on a former occassion by Mr. Talbot, and which Sir Anthony Carlisle has by an oversight attributed. in No. 809, to M. Daguerre, are not worth for a moment the attention of the artist, for, besides other defects, the lights and shades are reversed. Still the subject is curious, and to a trifling extent may be useful even at the present stage of its progress, where however it will not stop. The French, indeed, can show something more deserving of notice than these specimens, and what we conceive is totally different, both in the effect produced and in the process itself, except so far as the light of the sun is concerned.

The Lecture. Mr. Brayley's subject was "The equilibrium of the atmosphere, as dependant on the united action of gravity and temperature." The purport of this lecture was the introduction of some speculations concerning the mechanical constitution of the atmosphere. The Lecturer first imparted the usual information respecting its weight, its elasticity, the law of its pressure and density, its sensible height, as determined by different methods, and the opinions which have been held at various times as to its limits, until they pretty generally accorded with that inferred from the researches of Dr. Wollaston, of its being impossible that the rarity of the air can exceed that point at which the repulsive force between its partieles becomes less than the force of gravitation. He then adverted to

M. Poisson's hypothesis, according to which, the limit of the atmosphere, instead of thus being one of almost insensible gradation, is abrupt and well-defined, through a process in the upper regions of the air, no less singular than that of its conversion by cold into a liquid or even a solid. Without taking this extreme view of the subject, nor yet controverting it, the Lecturer contended that, admitting that extra mundane space to be colder than the mean temperature of the air, it must follow that, at a certain point in the rarity, or in the height of the atmosphere, an inverse order of its density commences; so that beyond the region of greatest rarity (greatest under the supposed conditions), another region exists, in which the density increases in some ratio with the altitude, but whether it terminates in the liquidity of the air, it was no part of his inquiry to determine.

He attributed this effect to the extreme cold which is supposed to reign in space, and advanced in confirmation of his views, the singular vaccillating appearance which is observed in the progress of the oscultation of fixed stars by the moon; that is, supposing the moon to have an atmosphere, and that it is similarly constituted. But what the Lecturer depended on principally for argument and illustration, is the remarkable deficiency of luminosity in a middle region of the atmosphere of comets, and which he had the authority of Sir John Herschell to attribute to the dissipation of its vapours by heat, and the luminous appearance of the outer region or coma, to the condensation of those vapours in an exterior sphere of greater cold. This he imagined to be a case in point, or analogous at least to his supposed constitution of the earth's atmosphere, the different nature of the wirial fluids being matter of no consequence. The only experimental illustration of his theory that he advanced, was the condensation of the attenuated vapour in Dr. Wollaston's cryophorous by the application of cold. This he gave as an instance of gradation in density, of a column of vapour as it approached the source of cold and became converted into water; and adduced the fact of liquefaction of the vapour, as a proof, as we understood him, of the high degree of density of the immediately previous and proximate state of the vapour.

Remarks.-M. Poisson, like a true mathematician, supports his hypothesis of the liquid state of the air at the extreme limit of the atmosphere, by a mere analytic investigation, resting on assumed atomic and other data, particularly that of the extreme cold existing in universal space-but which by the way is opposed to the deductions of M. Fourrier, also mathematically derived➡

means

and not only does he thus support it, without any reference to physical considerations and probabilities, and the recognised methods of legitimate induction, but in direct opposition to phenomena, particularly those which belong to optics. But Mr. Brayley, in behalf of his modification of, or rather addition to, Poisson's theory, argued the point on better grounds, and we will add in & more philosophical manner, by taking the principles and appearances appertaining to natural philosophy for his guide, though we greatly fear that they will by no bear him out in his views. We have, how. ever just given him credit, in one particular, for more than he really performed; he having strangely omitted the argument, and advanced only the evidence he was able to collect for the inference from it, that cold produces an increasing density in the upper regions of the atmosphere. We must also say, that of one portion of this evidence relating to the occultation of stars, it cannot be allowed him, if what astronomers inform us be true, that the singular appearance attending it, is not common to all the stars. And in regard to the supposed constitution of the atmospheres of comets, it scarcely amounts to analogical evidence, for their vapours are imagined to be condensed in the sense of incipient liquefaction by the operation of cold, and not brought into a state of greater density as an elastic fluid. The nature of the phenomenon, if it be such as Sir John Herschell supposes, is corroborative rather of Poisson's than of Mr. Brayley's theory, allowing only for that immense distance of separation between the particles of condensed vapour, which its extreme tenuity denotes, and which prevents the formation of anything more approaching to a liquid than a fog. But Mr. Brayley may say that

state of greater density in the elastic fluid must necessarily precede its condensation into liquescent or visible vapour. However this may be, the appearance alluded to as belonging to comets, gives evidence only in favour of the former fact, although it must have been in reference to the latter that Mr. Brayley could be supposed to have cited it. But what proof is there of the necessity just referred to? Does Mr. Brayley think the fact to be so established by the experiment with the cryophorous as to allow him to dispense with argument? It is scarcely necessary to say, and certainly it is not necessary to prove, that his statement of a difference in the density of the vapour in this instrument, being produced in proportion to its proximity to the source of cold, is by no means correct. The formation of water, to

which he pointed in proof of his assertion, was an inapposite fact, for the vapour was already of the greatest density consistent with its temperature, and on the application of cold, it collapsed at once into the state of water, without passing through any intermediate stages of density. Of course variations can be effected in the density of aqueous vapour, as well as in gases, and simply by the operation of difference of temperature, but it must be under other circumstances than those which were given. Cold, although spoken of in positive terms that are too apt to mislead, is not a positive but a negative cause, and cannot of itself produce an increase of density in air or vapour. It is an abstraction, or it is a diminution of repulsive force, but there the matter ends and the particles will remain as distinctly separate as before, unless there is an approximating force present, or elicited, to take advantage of the circumstance. But our limits are exceeded-still we must find room to say, that the lecture was very well got up.

NOTES AND NOTICES.

Launch of the Steamer Nicholai.-The ceremony of launching a splendid steam-vessel, named the Nicholai, took place on Saturday, from Gordon's Dock-yard, Deptford. She is the largest steamer belonging to Russia, and is intended to ply as a packet between Lubeck and St. Petersburgh. The Nicholai was built by Mr. Taylor, in the incredible short period of four months from the time of laying the keel, after the designs of Mr. Carr, of the firm of Ritherden and Carr, surveyors to the Hon. the East India Company. After being launched the vessel was immediately towed across the river to the establishment of Messrs. Seaward and Capel, of the Canal Iron Works, Limehouse, the firm to whom, by the special order of the Emperor, is entrusted the execution of the steam machinery. This machinery is to be precisely similar to that adopted on board her Majesty's steam-frigate the Gorgon, which has been so much approved of; and with a speed proportioned to that used in the construction of the wood work, the whole will be fitted up and the vessel entirely ready for sea in one month from the date of the launch. The engines will be of 240-horses' power, and the peculiar merits of the mode of construction adopted by the eminent engineers referred to are such that the machinery is greatly simplified, and the space which it occupies proportionably diminished. Thus the length of the engine. room in the Nicholai is only 45 feet, whereas on the ordinary plan it would exceed 62 feet. The advantage of having so much space in the most superior part of the vessel cannot be too highly estimated. This will be immediately evident form the fact that the Nicholai, of 800 tons burden, will carry 150 pas sengers-a number equal to that of the Great Western, of 1,400 tons. The success of the Gorg on, just returued from a six months' cruise on the coast of Spain, has been so pre-eminent that the Lords of the Admiralty have given orders for five more pair of engines on the same principle, to be fitted into five new frigates. One of these (the Coclops) will be of 1,300 tons burden, with engines of 320 horses power. She will carry 20 guns, and be the largest man-of-war steamer in the world.

foundation for the view which "Aquarius" is pleased to take of the subject.

To prevent wrong impressions, therefore, I think it right to state, in the first place, that the comparisons made by "Aquarius," and upon which the whole of his arguments are founded, viz.,between the last year of the old system, (that is of separate bodies of fire-men acting independently and regardless of each other,) and the results of the improved system, characterized as it is by concert and harmonious co-operation; these comparisons, I say, are unjust. Comparisons are odious," but especially so when founded on false premises.

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It may, perhaps, be in the recollection of most of your readers, that I commenced my annual report of London fires some time antecedent to the formation of the present Fire-Establishment; and that I have more than once explained that my source of information was then limited to the experience of one fire-office only. Now it must be pretty well known, that under the old regime, no one fireoffice in London was in possession of information respecting all the fires that occurred, nor of any thing like it; in fact, out of my own observations and attendance, I was frequently enabled to add to the list. Now, if we just compare this state of things, with the present very complete arrangements, by means of which every alarm of fire throughout the whole extent of this vast metropolis, be the result what it may, is reported twice a day to the head-quarters of the establishment, this alone would account for a vast discrepancy in point of numbers. I should like to know what sort of a fire-report I could have drawn up for 1838, had my sources of information been confined to the practical experience of the County Fire-Office, which continues to jog on in the unimproved state? I can vouch that it would have looked somewhat more companionable with its like of 1832, than did the voluminous records afforded by the comprehensive knowledge of the better plan. In the next place, the classification of the damages is now somewhat different to the former practice, making an apparent increase of serious fires, when the fact is, the per centage of really serious fires is very considerably reduced. Again, under the old system, fatal fires were seldom or ever reported. Under these circum

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stances, therefore, the disparaging comparisons instituted by "Aquarius," and so boastingly brought forward continually, are founded (as he well knows) on erroneous data, and are altogether false in the inferences attempted to be drawn from them.

It must be palpably evident, that the fire-men cannot prevent fires taking place, and that the number of these accidents may be expected annually to increase, with the spread of population and of buildings. Neither is it in the power of fire-men under all circumstances, to prevent the occurrence of serious fires, because it continually happens, that fires have really become what is now called serious, before they are discovered; in fact, I have already mentioned several instances in which total losses have actually taken place before the fire-men have been called out; and because the results are honestly reported, are these men to be censured by such hypercritical observers as 'Aquarius"? This writer says," the testing point of the firemen's success is the number of fires that are prevented from spreading to a serious extent after they are discovered." This list, then, in strictness, would include all the slightly damaged, and very many of the seriously damaged, with a tolerable share of the total losses!"

The

It is not, however, by a dry enumeration of number alone, that any correct idea can be formed of the good or ill success of the fire-men's exertions. ever varying circumstances of each particular case, require to be known and duly weighed, before any satisfactory conclusions can be drawn from them.

In the truly appalling list of last year's serious fires, I have entered into the details of most of them as far as was consistent with the limits of your work; and I would ask any intelligent and impartial reader, if there was a single instance in which blame would seem to attach to the fire-men. Take for example, the destruction of the Royal Exchange; there the flames had attained a most serious ascendancy before the fire was discovered-great difficulty arose in obtaining access to the building-water was with difficulty obtained, from the intense frost which prevailed-the building was filled throughout with timber galleries and passages most intimately connected-and yet some portions of the