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afloat as to the changes said to be go- situdes at the surface, which will ing on in our own climate, and when ever continue to renovate the face the problem of navigating the arctic of nature, to diffuse the heat equally sea has been again revived with re- throughout the whole mass. doubled interest. Meantime, we may It hence appears, that if we penetrate extract the account of some curious the ground in summer, it will be observations made on the temperature found colder and colder as we descend, of the ground at various depths, which and warmer and warmer in winter. form a striking illustration of the pro 66 The celebrated naturalist and accurate gress of heat downwards, and of the observer, Saussure, in the month of October principle on which depends the me 1785, made an interesting set of observa. thod recommended by Professor Les- tions on the banks of the Arve, near Genelie, of fixing the mean temperatures va. By digging downwards on successive of places by the temperatures of their days, he reached at last the depth of 31 springs,-a method which, from its feet. While the surface of the ground had superior accuracy and facility to the retained a heat of 600.3 by Fahrenheit's
scale, the temperature of the earth at the tedious, incorrect, and, in most cases, depth of 4 feet was 60°.8, at 16 feet 56°, impracticable one, by averaging the
at 21 feet 53o.6, and at 28 feet 51°.8. observations of a series of years, pro- A thermometer buried 31 feet deep was mises so much to advance our know- found, when taken up in summer, to stand ledge of this most important element at 49o.5, and when raised in winter, to inin physical geography and the theory dicate 52o.2. Notwithstanding this great of climate.
depth, therefore, it had still felt the vicissiSo slowly it appears are the impres- tude of the seasons, having varied 20.7 in sions of heat and cold conveyed through the course of the year. The extreme imthe mass of the earth, that the vary- pressions must have taken six months to ing influence of the seasons reaches penetrate to the bulb, since the tempera
ture was lowest in summer and highest in but to very moderate depths. Before
winter. the extreme heat of summer can pe
“But this plan of observing is clumsy and netrate to the depth of thirty feet, imperfect, there not being sufficient time it is stopt in its course, and par- to allow the mass of earth to regain its tially drawn back by the severity of proper degree of heat, and too u uch for the winter's cold, which it thus serves, the instrument to retain its impression unin some degree, to mitigate ; and this altered before it can be raised up and obis the reason why the frost, as appears served. In order to throw distinct light on from these experiments, scarcely ever
a subject so curious and important, Robert penetrates one foot into the ground. Ferguson, Esq. of Raith, a gentleman In the same manner, the cold of win- whose elegant mind is imbued with the ter, before it attain a certain depth, love of science, caused, lately, a series of is made to return and moderate the large mercurial thermometers, with stems warmth of summer. Part, however, cious garden at Abbotshall, about 50 feet
of unusual length, to be planted in his spaboth of the heat and cold, penetrate above the level of the sea, and near a mile still farther, and perform, at a greater from the shore of Kirkaldy, in latitude depth, the same species of ebb and 56° 10. The main part of each stem flow as at first. Thus a series of vi- having a very narrow bore, had a piece of brations, as it were, corresponding to wider tube joined above it ; and to support. the impressions of successive years, the internal pressure of the column of merdiffuses itself downwards, whose ex cury, the bulbs were formed of thick cy
linders. tent, however, decreases in such a ra
The instruments, inclosed for pid progression, as to attain the limit of protection in wooden cases, were then sunk our nicest instruments at a depth of per- four, and eight feet, in a soft gravelly soil
beside each other to the depths of one, two, haps 100 feet or less, where the tempe- which turns, at four feet below the surrature, therefore, is to sense quite per- face, into quicksand or a bed of sand and manent. But though thus enfeebled, water. These thermometers were careful. the impressions of heat still descend ly observed from time to time by Mr and augment, by insensible degrees, Charles Norval, the very intelligent garthe great store which is accumulat- dener at Raith ; and we have now before ed towards the centre, whence they us a register of their variations for nearly are again conveyed upwarıls to cor
three years.” rect any permanent inequalities, and, The following table exhibits the with the exception of those vicis. mean results for each month:
GEOMETRICAL VIEW, of some experiments on the temperature of the ground at various depths.
Therm? 1 foot deep
These observations, however, we est always attaining their limits latest; have thrown into the more striking and, in the case of the 8 foot one, form of geometrical curves, to which the midsummer's heat was not felt we request the attention of the read- till the middle of September, nor the er. (See Plate.)
winter's cold till the middle of March. The dark waving line which occu- But the most remarkable circumstance, pies nearly the whole compass of the and that which, if future observations plate, represents the gradation of the confirm it, will afford the most imthermometer which was planted one portant results in finding the mean foot deep, and the other lines as ex- temperatures of places, is that about pressed in the plate itself. The dis- the middle of May 1816, and of April tance of any point on any of the lines 1817, also in October of both years, from the bottom of the plate, where the various lines, at least the three the corresponding month is marked, deepest, cross each other ; indicating indicates the temperature of theground that at these times the thermometers at that time, which is measured by marked all nearly the same temperathe degrees marked in the sides. ture, in May somewhat below the Thus, for example, in the middle of mean, and in October about as much May 1816, and it is a very remarkable above it. Hence we may derive the point, the temperatures at all the dif- maxim, that if, by measuring the ferent depths were the same, and temperature of the ground two or three nearly 44°. These curves present a feet deep, we seek an approximation view of the progress of heat, which is to the mean temperature of any place not a little curious and interesting; an element of such importance in phythe dark line rises ncarly to the top, sical geo-raphy, and the theory of cliand falls nearly to the bottom of the mate, and rendered still more so, since plate each year, thus indicating the we can now find, by its means, the great range of the thermometer one elevation above the level of the sea foot deep. The others present a smaller and smaller range, in proportion to the depth, and the line which • The very simple rule for this purpose, would represent the gradation of the given by Professor Leslie, is to allow 100 thermometer at a still greater depth, yards of elevation for every degree that the would gradually merge into the straight mean tenperature of the place decreases line of the mean temperature. The below that of the level of the sea, in the different points of the plate also,
same latitude, found from a table which where the lines are highest and low- thing,” says he, “ could tend more to cor
we shall give in our next Number. “ No. est, shew the different times at which rect our ideas of physical geography, than the several thermometers arrived at
to have the principal heights in all coun the maxima and minima, -the deep- tries measured with some tolerable degree
these observations should be made tervals, is the effect of a general prinabout the end of May, when the re- ciple, and will be renewed with the sult will be a little too small, or still seasons, there can be no doubt, and better about the end of October, when, the following seems to be the process if any thing, it will be too great. by which this is effected. About the
Such are some of the results dedu- middle of winter, or somewhat later, eible from even this single register. when the surface of the earth has ata Of what importance, then, is it to tained its greatest degree of cold, the multiply observations of this kind, of increasing influence of the sun begins so easy execution, in different parts of to pour in a continued stream of heat, the country? We would recommend increasing in intensity, till somewhat this to all who are interested in the pro- beyond the middle of summer, when gress of science. * Numerous registers the ground will have attained its of the temperature of the air are kept greatest heat, and when the first and in different places, but, though these ob- feebler impressions of the annual supservations may one day prove of the ply, only beginning to be felt at the highest consequence, we still think depth of 15 feet, the intermediate that, in the mean time, it would be more portions of this stratum of the earth important to observe the temperature will be warmer and warmer towards of the earth, which, retaining and ac- the top. The influence of the sun, cumulating the solar impressions, however, being now on the decline, gives us more expeditiously the mean and the impression of his extreme heat of the whole. We may also observe, moving downwards, the surface will that the observations of a few ther- begin to get colder than the stratum mometers at different depths, by shew- immediately below it, which will ing the law of the progression, en become the hottest part of the mass ; ables us to see a good deal deeper, and, the fluid of heat continually enwithout actually making the observa- deavouring to recover its equilibrium, tions. The gradations of thermome- while this focus will still keep up the ters, for example, at 2, 4, 6, 8, and 10 flow towards the centre, it will likefeet, would enable us to fix the gra- wise send off an ascending current, to dation of one at 20 feet, withont ac- supply the deficiency from above. tually descending to that depth. The accumulation, therefore, at length Hence, in the above observations, the entirely dispersing, will diffuse . deepest thermometer might almost pretty uniform temperature through. have been dispensed with, for we have out the whole stratum of 30 feet. All calculated its indication by means of the thermometers to this great depth the first three, and the results agree will be nearly alike the curves which most remarkably with observation.
represent their gradations, will all That the above circumstance of the meet together, and this happened, lines crossing each other at stated in, according to the above observation, in
the month of October.
But the influence of the sun still of precision. In this way is traced a profile, or vertical section, which exhibits at decreasing, the
ascending current will one glance the great features of a country."
still continue flowing from a greater In a former Number, we pointed out the and greater depth, even to 30 feet, importance of extending this principle even
where the heat of the mass will at to the making of models of elevated tracts length become the greatest, and where, of country, and mentioned that we had re as from a new focus, the remains of commended this to the attention of an artist the supply of the year will still send in this city. We are now happy to be able down likewise a current below. This to state, that this gentleman, who is also in will happen about the middle of winthe practice of constructing profiles and sections on the most scientitic principles, is ter, just as the effects of the succeedproceeding with a model of Solisbury Craigs, the surface; and as it is clear, there
ing year are beginning to penetrate a spot so remarkable in the history of geo- fore, that this second annual supply, logy.-Ed. To the agriculturist these observa
which begins to flow downwarıls ations would prove amusing, instructive, and perhaps not devoid of practical utility, Estimating the degree of penetration to whom, at least, it is always of conse at the rate of one inch every day, and exquence to know his elevation above the le- cluding, at present, the effect of preceding val of the sea.