The very beautiful "Dirge,” by the late Dr Leyden, has just come to hand, and will certainly be inserted. The communication from J. F. reached us too late to be rendered available for the present Number; but he may be assured of our early attention to his proposal. The intelligent author of "Scottish Zoology" will easily understand our reasons for delaying his last communication till next month. The articles on "Scottish Lunatic Asylums," and “ Prince Henry;" and the excellent "Transla tions from Petrarch,"-also in our next. "Philo" is no ordinary person; but it is necessary that he should enable us to correspond with him before the articles with which he has favoured us can appear, We must request J. C.'s patience a little longer, but he is not forgotten. We will correspond with Z.-meanwhile he has our best thanks. "Charity," "Sensibility," and "Marriage," are all really very good; but we fear they have the mortal sin of being too serious. Does "Miles" ever permit a newspaper advertisement to appear in his drawing-room? Our excellent friend S. has undoubtedly forgotten that we always publish about the 20th of the month: had his articles arrived a few days sooner, they would have appeared in our present Number. The Correspondents of the EDINBURGH MAGAZINE AND LITERARY MISCELLANY are respectfully requested to transmit their Communications for the Editors to ARCHIBALD CONSTABLE and COMPANY, Edinburgh, or LONGMAN and COMPANY, London, to whom also orders for the Work should be particularly addressed. Printed by George Ramsay & Co. THE EDINBURGH MAGAZINE, AND LITERARY MISCELLANY. APRIL 1818. ORIGINAL COMMUNICATIONS. ON CLIMATE. THAT striking diversity of climate which we observe on the globe, is one of the most important arrangements in the economy of nature; and nothing can be more interesting than to trace the circumstances by which so curious a disposition is brought about, -the process by which the constant and equable flow of heat from the sun to the earth is so unequally distributed over its surface. Notwithstanding the progress of science, this branch of physics is still but imperfectly understood, and is generally treated, indeed, in rather a loose and unsatisfactory manner. In the very interesting paper, however, under the word Climate, recently published by Professor Leslie, in the Supplement to the Encyclopædia Britannica, the subject is treated in a manner suitable to the talents, the extent of information, and the peculiar researches of this distinguished philosopher. The paper contains a clear exposition of the great principles on which the laws of climate depend, *—a rigorous calculation of the various circumstances which may affect the results,-a store of curious and instructive facts to illustrate At least as to the distribution of HEAT, that of MOISTURE being deferred to ano ther part of the same work. and confirm the deductions of theory, -and also a most interesting account of the author's own discoveries, and of the refined instruments which he has contrived, to measure the influence of those great natural agents, on whose operation the laws of climate principally depend,-discoveries and inventions which, we have no doubt, will form an important era in the history of the sciences to which they relate. For, if the invention of the thermometer and barometer, and the knowledge of the weight of the air and its gradations, have so greatly accelerated the progress of science, we may certainly expect the most important consequences from an exact knowledge of the gra dations of climate as we ascend the atmosphere, from the detection of a new principle, which spreads the influence of heat and cold through this great fluid element, with the diffusive rapidity of sound,—and from the invention, among other instruments of extreme delicacy, of one which, quite insensible to the heat and light of the ambient air, yet marks, in a clear day, the impressions of temperature from the most distant sky. In our next number we hope we shall be able to give such an abstract of this important article as our limits will allow, peculiarly important at present, when such speculations are afloat as to the changes said to be going on in our own climate, and when the problem of navigating the arctic sea has been again revived with redoubled interest. Meantime, we may extract the account of some curious observations made on the temperature of the ground at various depths, which form a striking illustration of the progress of heat downwards, and of the principle on which depends the method recommended by Professor Leslie, of fixing the mean temperatures of places by the temperatures of their springs,- -a method which, from its superior accuracy and facility to the tedious, incorrect, and, in most cases, impracticable one, by averaging the observations of a series of years, promises so much to advance our knowledge of this most important element in physical geography and the theory of climate. So slowly it appears are the impressions of heat and cold conveyed through the mass of the earth, that the varying influence of the seasons reaches but to very moderate depths. Before the extreme heat of summer can penetrate to the depth of thirty feet, it is stopt in its course, and partially drawn back by the severity of the winter's cold, which it thus serves, in some degree, to mitigate; and this is the reason why the frost, as appears from these experiments, scarcely ever penetrates one foot into the ground. In the same manner, the cold of winter, before it attain a certain depth, is made to return and moderate the warmth of summer. Part, however, both of the heat and cold, penetrate still farther, and perform, at a greater depth, the same species of ebb and flow as at first. Thus a series of vibrations, as it were, corresponding to the impressions of successive years, diffuses, itself downwards, whose extent, however, decreases in such a rapid progression, as to attain the limit of our nicest instruments at a depth of perhaps 100 feet or less, where the temperature, therefore, is to sense quite permanent. But though thus enfeebled, the impressions of heat still descend and augment, by insensible degrees, the great store which is accumulated towards the centre, whence they are again conveyed upwards to correct any permanent inequalities, and, with the exception of those vicis situdes at the surface, which will ever continue to renovate the face of nature, to diffuse the heat equally throughout the whole mass. It hence appears, that if we penetrate the ground in summer, it will be found colder and colder as we descend, and warmer and warmer in winter. "The celebrated naturalist and accurate observer, Saussure, in the month of October 1785, made an interesting set of observations on the banks of the Arve, near Geneva. By digging downwards on successive days, he reached at last the depth of 31 feet. While the surface of the ground had retained a heat of 60.3 by Fahrenheit's scale, the temperature of the earth at the depth of 4 feet was 60°.8, at 16 feet 56°, at 21 feet 53°.6, and at 28 feet 51°.8. A thermometer buried 31 feet deep was found, when taken up in summer, to stand at 49°.5, and when raised in winter, to indicate 52.2. Notwithstanding this great depth, therefore, it had still felt the vicissitude of the seasons, having varied 2°.7 in the course of the year. The extreme impressions must have taken six months to penetrate to the bulb, since the temperature was lowest in summer and highest in winter. "But this plan of observing is clumsy and imperfect, there not being sufficient time to allow the mass of earth to regain its proper degree of heat, and too much for the instrument to retain its impression unaltered before it can be raised up and ob served. In order to throw distinct light on a subject so curious and important, Robert Ferguson, Esq. of Raith, a gentleman whose elegant mind is imbued with the love of science, caused, lately, a series of of unusual length, to be planted in his spalarge mercurial thermometers, with stems cious garden at Abbotshall, about 50 feet above the level of the sea, and near a mile from the shore of Kirkaldy, in latitude 56° 10. The main part of each stem having a very narrow bore, had a piece of wider tube joined above it; and to support. the internal pressure of the column of mercury, the bulbs were formed of thick ey linders. The instruments, inclosed for protection in wooden cases, were then sunk four, and eight feet, in a soft gravelly soil beside each other to the depths of one, two, which turns, at four feet below the surface, into quicksand or a bed of sand and water. These thermometers were carefully observed from time to time by Mr Charles Norval, the very intelligent gar dener at Raith; and we have now before us a register of their variations for nearly three years." The following table exhibits the mean results for each month: |