must necessarily be less exact: those, however, here related, do not require the aid of very minute investigation; and being made without reference to any pre-conceived theory, their accuracy may be more safely relied upon. The circumstance of evaporation taking place, from snow and ice, when the cold is below the freezing point of water, apparently without the degree of heat necessary to liquefy it previous to its conversion into vapour, is already familiar to natural philosophers; the extent to which this takes place cannot be ascertained in this climate, where the thermometer seldom indicates for any considerable time a temperature below 32°. Fahrenheit. At the time of my residence in America, I was not informed that any observations had been made on the subject, and consequently remarked the phenomena with more attention. I shall, in the first instance, relate the circumstances which directed my attention to the subject; and then give a short detail of an experiment made with a view of elucidating the appearances I had observed. In America, as in Russia, it is the custom to preserve meat in a frozen state during the winter. Meat thus preserved, I remarked to be less juicy than such as was recently killed; and on weighing a definite quantity of recently killed meat, and the same meat again after a two months' exposure to the air in the coldest season of the year, I found a very considerable deficiency. I observed also, that wet clothes hanging out on the lines, in a few hours, became dry and supple, notwithstanding the thermometer at the time indicated a temperature many degrees below Zero. It is a remark very generally made, in the part where I resided, and I am inclined, from my own observation, to think it correct, that the snow diminishes much in the winter months without the aid of liquefaction. Observations of this kind are made with greater accuracy than might be supposed, as generally speaking the most considerable falls of snow take place early in the season, mid winter being characterised by a continuation of clear cold weather without the occurrence of any considerable falls. The circumstance, however, which more immediately directed my attention to the subject, was an appearance observed on the ice of Lake Wenepie, on the borders of which I was then resident. This extensive piece of water is always frozen over to a considerable depth in the winter; but its surface by no means presents a regular or uniform appearance. At the commencement of winter, when congelation has taken place to the depth of a few inches, the occurrence of a strong wind will cause it to break up, and separate into smaller pieces of a tabular form, which being driven into confused heaps by the waves, become disposed edgewise, forming various angles with the general surface of the lake. These tabular pieces or slabs of ice, cemented by the frost in the positions described, are exposed freely to the atmosphere during the continuance of winter; and I observed the angles in all of them to be rounded off, and apparently eroded by the atmosphere in a degree proportioned to the length of time they had been exposed. Some of them, on which I made more particular observation, in the winter of 1813, decreased considerably, becoming thinner and more transparent. These observations induced me the succeeding winter to make the following experiment. On the 28th of November, 1814, being at that time about the middle of the eastern coast of Lake Wenepie, in latitude 52° N. I hung up in an open shed, where it was freely exposed to the air, but where the sun had no access, a flat slate of ice about two inches thick, which weighed accurately in the steelyards twenty lbs.To ensure accuracy no one but myself had admission into the building. On the 14th of February it had sustained a loss of seventeen ozs. the highest temperature in the interval, being 23° above Zero. As the loss of weight was more considerable than I had expected, I again weighed it on the 20th of the same month, and found the deficiency twenty ozs.; the highest temperature from the 14th to the 20th, being 14o above Zero. Beyond this time the experiment was not so satisfactory, the thermometer having indicated on the 26th and 28th days of February a temperature of 360 for upwards of two hours each day: no dropping, however, took place from the ice, nor could I perceive the least moisture upon it. In March the thermometer was uniformly below the freezing point of water; the average temperature in the middle of the day being 14o above Zero. On the 7th day of that month the ice had lost 2 lbs. and on the 31st, beyond which time the experiment was not continued, its total loss was 4lbs. or a fifth part of its weight. My next experiment was on snow, which for the purpose of securing a free admission admission to the atmosphere I inclosed in folds of crape. The snow and its covering weighed on the 16th of February thirty ozs. It was hung up in the same place, and with the same precautions as the ice. In ten days it had lost two ozs. and in the nine following days two ozs. more. On the 14th of March, the crape through the whole process remaining perfectly dry, its total loss was six ozs. or a fifth part of its weight in twentysix days. When we consider that the ice and snow in these experiments were not exposed to the sun, and that the wind had but partial access to them, it can scarcely be doubted that the diminution was not equal to what it would have been in a more exposed situation. Admitting, however, the grand operations of nature to be only effected in the degree which took place in the above imperfect experiment, the cause of the diminution, whatever it be, must have a powerful agency in regulating the state of the atmosphere, and highly deserves the attention of those whose pursuits are directed to that department of science.* The origin of the atmospherical vapour, and the manner in which it is acquired by the air, have been the objects of much discussion amongst natural philosophers, but I am not aware that any explanation has been given of the diminution of ice under the circumstances observed in the foregoing experiments. The opinion of Dalton and Saussure, that caloric only is the cause of the atmospherical vapour, must, I think, be materially discredited by the facts alluded to: nor is the explanation afforded by the opposite theory of vaporisation being produced by an affinity between the atmospherical gases and water without its difficulties, as it is not easy to conceive how solution by the air can take place without the ice being previously liquefied by caloric. Perhaps, however, this circumstance may be explained, by supposing the affinity between air and water to be so strong as to occasion the ice by a kind of disposing affinity to attract the degree of caloric necessary to its liquefaction, from an atmosphere even at the reduced temperature of that in which the experiments were made. From a review of the ingenious experiments made by Dalton, The author's ingenious theory of eva poration resulting from the above observations will be given in our next. it appears evident that water can exist in a state of vapour by the aid of caloric only, no atmospheric air or other gaseous solvent being present: it is also, I think, equally evident that the atmosphere at reduced temperatures is capable of combining with ice either without the degree of calorie necessary to its liquefaction, or by exciting so strong an affinity for water in the manner before alluded to, as to absorb and retain a portion of it in a fluid state, notwithstanding the degree of cold existing at the time. It appears to me, that each of these operations takes place in the chemistry of nature, and that the true theory of the atmospherical vapour is to be found in a combination of the two theories, which for some time have engaged the attention of chemists. In all temperatures above 32° Fahrenheit, water may be conceived to be taken into the atmosphere partly by the agency of caloric, and partly by a very weak affinity excited between it and the air; this loose state of combination is highly favourable to vegetation, as the nearer the atmosphere approaches to the point of saturation, its precipitations of dew or rain will be more abundant. In temperatures below 32°, and the supposition is rendered more propable by the experiments of Bettancourt, caloric seems to have no power of producing the vaporisation of water: it is, however, abundantly evident from the experiments on ice before mentioned, that air at these reduced temperatures has the property of taking it up; and as an opinion I would wish to suggest (for I am not aware of any experiments which either confirm or refute it) is it not possible that this solvent property of the air may increase in a direct ratio with its privation of caloric? The following circumstances, if they do not prove the opinion correct, will at least shew it to be not altogether improbable. That the atmosphere when its temperature is below Zero has a strong attraction for water, is evident from the dense exhalations which are seen to arise at those times from such parts of rivers, or lakes, as remain unfrozen, a circumstance which frequently takes place where the current is strong, or the depth of water very considerable. What, however, I more particularly wish to urge, is, that these exhalations increase in density, and apparently in quantity, in proportion to the coldness of the air. I have never seen the particular kind of exhalation to which I at present allude, when when the thermometer indicated a tem perature above 3° Fahrenheit, but they invariably take place when the temperature is below that point, as far as my observation goes, and without being influenced by the varying weight of the atmosphere. These mists or exhalations are so copious that from the unfrozen ocean, or any other extensive surface of water, they have the appearance of dense white clouds, very little shaded, driven before the winds, or rising perpendicularly, and at length dissolving in the atmosphere. When the weather is extremely cold, their density is so great as to resemble that arising from lime when water is thrown upon it-The air at very low temperatures is remarkably dry, containing no water in a loose state of combination, or such as is held in solution by caloric only. Assuming as correct the principle on which Mr. Leslie has formed his hygrometer, that the dryer the air is the quicker evaporation is conducted a principle which was, I believe, in the first instance advanced by Dalton, an atmosphere under those circumstances will have a much stronger attraction for water than an atmosphere at higher temperatures surcharged with the vapours formed by caloric.-Besides the arguments already stated in support of this opinion, it may be remarked that the solvent properties of any gaseous body, and of some fluid bodies, will increase in proportion to their degree of condensation. Setting aside barometrical pressure, for of that unfortunately I had no opportunity of making observations, the mere abstraction of caloric from the atmosphere will cause a very material diminution in its bulk, by which means a greater weight of air will be brought to act at once on the ice; and the opposition which its elasticity forms to its combination with other substances will be much lessened. Sensible that many arguments may he brought against this hypothesis, and being by no means assured of its accuracy, it is with extreme diffidence that I have ventured to suggest it. The facts, however, mentioned in this paper may be entirely depended upon; and I shall be extremely happy to see them converted to a better purpose by the ingenuity of others. Regarding the facts, however, as unquestionable, it must, I think, be evident that the snow and ice in the arctic regions are continually undergoing a material diminution by the constant operation of the cause MONTHLY MAG. No. 837. mentioned. Instead of the gradual and perpetual accumulation of snow and ice which some have imagined to be constantly taking place in those regions, and rendering them inaccessible to mankind, we see a power continually at work, which must certainly materially retard such an accumulation; and perhaps, when better understood, and when those regions shall be more perfectly explored, may be found adequate to prevent them altogether, or at least' to prevent their acquiring a magnitude and weight, inconsistent perhaps with the general welfare and safety of the globe. Dec. 6, 1819. GEO. HOLDSWORTH. 53, Upper Mary-le-bone-st. To the Editor of the Monthly Magazine. SIR, T has often been wisely, though per 66 haps somewhat quaintly observed, that there is a Providence in every thing." This fact has, of late, received most pleasing and ample confirmation, in the numerous benevolent Institutions and Societies to which the ignorance, the vices, and the bodily wants of a great portion of our fellow-creatures have given rise. To their Ignorance are we indebted, as a first motive for the establishment of numerous Schools, in which learning may be acquired at a comparatively trifling expence. Their Vices have called forth some of the very best feelings of our nature, and the exercise of the highest and noblest of the Christian Virtues; whilst the Physical wants of the Poor have elicited Charities, and called into action principles in numerous quarters, where they might otherwise have lain dormant. In fact, Mr. Editor, we may almost say, the Poor have been their own almoners; and even their very frailties have catered for their own amelioration; in all this I think I perceive the hand of Him who, "from seeming evil still educes good." Numerous, however, as are the means of relief to the Poor, the sluices of benevolence have not yet been all opened; and it is under this impression that I beg leave, through the medium of your Miscellany, to draw the attention of the opulent public, "particularly that portion of the British public whom Mr. Ledyard, in his beautiful Poem, on the character of the Fair Sex, describes, to the present very diminished use of Straw Hats and British Lace. Owing to this circumstance, numberless are the poor women and families now in a state of the utmost distress, who have heretofore derived subsistence and comfort from their industry in these particular branches of manufacture. It gives me, however, sincere satisfaction to have authority to inform you that this subject has already roused the sympathies of several distinguished ladies of the highest rank and influence in the country, who have most patriotically and benevolently resolved to give encouragement to a design for removing this great evil, and to hold forth the hand of encouragement to their less affluent fellow-countrywomen. Amongst these Ladies, I am proud to notice the names of their Royal Highnesses the Duchesses of Gloucester and York, the Duchesses of Rutland, Wellington, and Leeds, the Marchionesses of Salisbury, Stafford, and Worcester, the Countesses of Harcourt, Jersey, and Grosvenor, the Honourable Mrs. Villiers, the Honourable Mrs. Wellesley Pole, &c. &c. &c. And I mention this circumstance merely that by giving circulation to the gratifying fact, others may be induced to "go and do likewise." Ludgate-Street. WILLIAM CORSTON. ORIGINAL POETRY. LIBERTY. A Dithyrambic Ode, inscribed to SIR FRANCIS BURDETT. By William Duckett, of Paris. STROP' I. But borne on Homer's eagle wing, USE, source of life, Effulgence bright? No glorious deeds provoke the strings, M Daughter of uncreated light! Who seated near th' eternal throne, ANT' I. Inspir'd by thee, with hands of fire, STR' II. What laurel'd chief, what scepter'd king, No great, no gen'rous virtues fire. 'Midst marshy wastes and barren sands, EPODE. If led by Fancy o'er the plains, "Tis chance and gold that battles gain. Whole years of barter'd, ill-earn'd fame! At crimes that vengeanes would reprove, STR' I. From kings and warriors turn, my mind! ANT II. voice divine of deathless song! sacred strains that Bards inspire! To you eternal days belong, O wake to fame fair Freedom's Lyre? At Freedom's shrine my vows I pay, Let her alone inspire the lay; Invok'd by me she stands confest And all her influence fires my breast! So she inspire, let Phoebus dwell By me uncall'd in Delphic cell, And uninvoked th' Aonian train On Helicon or Pindus reign! EPODE. Thy voice, O Freedom! arts obey, And lawless tyrants feel, tho' late, Blood only can-blood expiate! Eternal Fame thou shalt receive, If verse Eternity can give; To time's remotest days, beliere, The Poet's and thy name shall live! SNOW. Feathery showers from Winter's throne, On whom the moon in silence dwells The beauty of his breath, Over vales and mountains driven, To lucid rivers;—— aye, Like joys the human heart hath felt CONTENT. J. R. PRIOR. |