published by Longmans,] under what heavy discouragements of loss of time, of labour, and of means, it was brought to the stage at which it was exhibited in the Great Exhibition of 1861, and subsequently deposited in the South Kensington Museum. The "Difference Engine," as it was called from the principle of differential tables on which it was constructed, was commenced in 1823; and its construction occupied the greater part of twenty years, being only abandoned finally in 1812. During that period Mr. Babbage expended upon it £20,000 out of his own private resources, Government having contributed other £17,000. The principle cbject of the invention was to calculate and print Astronomical and Nautical Tables, which often involve such vast arithmetical reckonings, that the possibility of economizing mental labour by means of machinery becomes an object of great importance. It is difficult to master Mr. Babbage's theory, even with the detailed account he gives of his invention; and to state it here, within reasonable compass, is impossible. But the leading principle can be readily apprehended; and as the reader is led on from stage to stage of the process, his mind comprehends the possibility of its indefinite extension. The only limit is the number of wheels put together. Perhaps the readiest illustration of the principle of construction is by reference to the ordinary gas-meter, with its wheels marking units, tens, hundreds, and thousands. But the superior constructive genius employed upon the Difference Engine may be conceived when we recollect that it works out problems by addition, subtraction, multiplication, and division, on any given rule, the "dot and carry one offering no obstacle to the progress of the calculation.

Mr.

Babbage is very severe on several members of successive Cabinets for declining to provide him with the means to enable him to complete and perfect his mechanism, which, as he says, in reference to the Tory ex-Chancellor of the Exchequer, "might possibly enable him to unmuddle even his own financial accounts." There is seldom much sympathy between the philosopher and the politician; and we are bound to confess that Mr. Disraeli could not be greatly blamed for declining to pledge the Government to provide the means of completing an invention, of the cost of which Mr. Babbage never could, or at least never did, give him any idea. It is satisfactory to learn that Mr. Babbage has preserved the materials for constructing the Analytical Engine,—a me

chanism still more efficient as a calculator than the Difference Engine. And, while the ingenious inventor may readily be excused for complaining that he has had no substantial fruit of his labour, he must seek to console himself by the reflection, that his case is not singular, and that when his great work is carried to a successful termination, under happier auspices, his name will always be honourably associated with it, as the skilful and sturdy pioneer who opened up the way and drew up the itinerary for scientific followers. So far as fame may be considered a reward, Mr. Babbage has not had to wait for it till he has no interest in it. A Russian Count, on his arrival in England, told the author, on meeting him at a friend's house, that the subject on which the Chinese savans were most anxious to have information from him was Babbage's Calculating Machine. On being further asked as to the nature of the inquiries, he said that they were most anxious to know whether it would go into the pocket. Upon which Mr. Babbage told the count that he might safely assure his friends in the Celestial Empire that it was in every sense of the word an out-of-pocket affair.- Edinburgh "Daily Review."

KEEPING OUT FROST.The leading principle of all protective measures may be stated to be not so much keeping out frost as keeping in heat. If any one will take the trouble to examine a bed of snow when it has lain upon the earth a day or two, it will be found that, however hard frozen on the surface, it is actually thawing where it rests upon the earth. If the snow be very thin, this may not happen to be the case, because the cold air may penetrate through it, and cause it to freeze to the soil; but when deep snow has lain some time, it invariably begins to thaw next the soil, however hard it may freeze at the surface exposed to the atmosphere. Another lesson of value may be gained by dipping some water from a well; it will come up comparatively warm, and its temperature probably 40° to 50°, according to the depth and the so:1. The inference from these two observations is obvious enough: the earth is a reservoir of heat, and this heat it is the gardener's business to make the most of, and all protective measures should have for their object to prevent its escape. This earth-heat is a matter of some importance to the life of plants when its amount is considered. On the 30th of December last the temperature of the earth at two feet from the surface

was 46° Fahrenheit. Since the frost set in, the temperature of the earth at that depth did not much decline. This heat is constantly rising to the surface; Lesce, if we pile up a mass of material of any kind, and leave it for some days, however hard it may get frozen, it will be found that when removed the earth is quite warm on the spot it has covered,-a simple consequence of the heat having been confined. The heat of the earth varies much near the surface as the seasons revolve; but the deeper we descend the less is the variation. It is especially worthy of notice that the soil is such a tad conductor of heat, that even at very triting depths the variations do not keep pace with the changes of atmospheric temperature, and this leads to very interesting results. By the elaborate experiments of Professor Forbes it was shown that at three feet the greatest cold does Det occur till February; at six feet, not till March; at twelve feet, in April; and at twenty-four feet in July. These facts aplin why water from deep wells is (as people say) cold in summer and warm in winter. At a depth of two feet the tempera ure usually rises considerably from the middle of April to the middle of July, and is in some seasons subject to many fluctuations: but during autumn, and the early part of winter, much of the heat absorbed during summer is retained by the crust, and plants exposed to severe frosts are still warm at their roots; and the atmosphere is so far affected by the radiation of heat from the earth, that early frosts are considerably modified in their effects.-Hiblerd's Gardener's Magazine.

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A GRAND LAMASERY, THIBET.— After having ascended and descended mountains for several days, we reached at length the summit called Ly-Tang, on which, for the first time during ten days' journey, we came to a settlement, consisting of several houses; we could not call it properly a city, nor yet a village. There is a large plain surrounding those houses, but it is quite uncultivated; there not a single field or even a tree to be en that could break the monotony of this arid waste; the only sounds to be heard were the cries of the eagle or the crocking of crows. A little higher up than Ly-Tang, and on the declivity of a hill, stands the grand Lamasery, rather regularly built, and having the appearance of a town in itself. Toward the summit are seen three gilt domes, glistening in the sun's rays. The houses, painted red, are the private dwellings of

the religious of the Lamasery. During the day those dwellings are nearly all shut up and silent. Let us enter under the grand dome in the middle, and see what is there passing. On the threshold of the large door, one hears harsh and cracked voices murmuring together. A number of men, bowed down, and each almost covered up in a large reddish shawl of serge, are then seen in the middle of the vast hall: those are the Lamas reciting their prayers, a jargon of words, the sense of which is unintelligible to them, and which are addressed to a very shadowy divinity.

Let us go into the interior. Behind a large curtain, raised up for our benefit, we behold a vast sanctuary, divided into several long and narrow aisles: it is here all the Lamas meet to pray in choir; they lay themselves along each side of the gallery on raised benches. The interior of the sanctuary is draped with variouscoloured cloth, and at the end is seen the statue of Budha, the centre and object of all their worship. From thence we proceed to the first storey, where we are invited to enter an office, and to sit down on our heels, while they present us with some tea with butter in it. The Lama administrator entertains us most graciously and gaily, all the while rolling his beads between his fingers; an insupportable odour of burnt butter, however, almost suffocates us, though we try to keep a pleased expression on our faces, lest we might appear to contemn our hosts. After having drunk the tea, we are made to ascend a ladder, which brings us to the residence of the living Budha: it is a well-paved apartment, decorated on one side with a number of little superstitious images, and on the other by a pretty library in excellent order. I watch with impatience to get a sight of the Budha; but I behold only a throne, and no one seated therein; a rich mantle lying on it shows only that some one is occupying the place. We ask our guide where he is, but are informed that he is lately deceased, though he has again been born in the very town within the last few days. We all know that the Thibetians believe in the transmigration of souls. After this, we are again made to mount another ladder, which brings us to the top of the edifice. The grand dome, that we had perceived so far off, is covered over with gilt copper; at the four corners are suspended bells, which the wind causes to ring, and which are supposed equivalent to a prayer. At another side, on a terrace, there has been formed a line of cylinders made of wood, which

the wind also turns, and on each of which characters are traced, forming, all together, a prayer. This instrument is called a korlo. When the wind blows, the korlo turns, and the korlo prays. Besides the wind-korlo, there is another used which is turned by the stream; this is named water-korlo it is kept constantly in motion. To these two is added the simple korlo, which is turned with the hand. In every village, in each house, and on every road, the Thibetian carries his inseparable korlo, and has thus the advantage of being able to pray without even thinking about it, and while conversing even with his neighbour. cording to the Lamas' belief, every object on which a prayer is written or engraved, when put in movement, prays; and as often as it moves, so many times do they consider the prayer said. For this reason, they have long poles fixed to their houses, to which are attached long bands of linen entirely covered with written prayers; each time the flag is made to float in the wind, the prayer is recited; and, as it blows very frequently in Thibet, the flag is supposed to gain considerable merits for its proprietor.Abbé Durand.

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COMPARATIVE VALUE OF MONEY

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DIFFERENT PERIODS.-It is a matter of great interest, but of considerable difficulty, to determine the amount which a sum of money at any remote period represents at any other, or the purchasing power any two such periods of any specified sum, say £100,-meaning by "purchasing power" the capacity of buying like qualities of like articles of convenience and comfort. The difficulty arises chiefly from the circumstance, that we have not a sufficient number of authentic facts for

the purpose. We might adopt, as the basis of our calculations, the wages of an agricultural labourer at any particular period, and the articles he could buy with such wages. But in times so remote as the thirteenth century, we have very few statements as to the amount of wages, and we have even reason to believe that a farm-labourer then received some food or clothing in addition to his wages. Our calculation would, therefore, rest on an insufficient basis; but an attempt may be made to reason on such facts as we do possess. Thus we find that in A.D. 1272, a labourer received 14d. a-day, or 9d. a-week. About that time, wheat varied from 20s. a quarter at Northampton, 17s. at Bedford, and 13s. 4d. at Dunstable, in A.D. 1258, to 6s. 8d.,

in A.D. 1270, and 4s. 6d. in A.D. 1281. The average may be taken at 12s. a quarter, or 1s. 6d. a bushel. A farın labourer, therefore, according to this calculation, could buy half a bushel of wheat with his week's wages. At the present time, we may fairly take the average wages of an agricultural labour at 12s. a week, and the price of wheat at 56s. a quarter, or 7s. a bushel. A labourer, therefore, could now buy more than a bushel and a half of wheat with his week's wages. It might from hence be inferred, that a labourer was threefold better off now than in the thirteenth century; but as already stated, we are tole rably certain that he then received other kinds of payment in addition to his wages; and it is necessary also to know what he had to pay for such things as he had to buy; but we have no facts of any value to guide us. We read of a fat ox being sold for 16s. in A. D. 1279, and a salmon for 5s. in winter, and 3s. in summer; but we do not know the weight of either one or the other; and so it is with other articles. A comparison of wages and prices at those remote times affords us, therefore, very little help in arriving at a conclusion as to the comparison between the power of buying, and the quantity that could be bought for any given sum. The fact which it is desirable to ascertain, or the question to be answered, is,-What quantities of like articles of necessity, luxury, and comfort, can a man, at any particular period, obtain for a certain sum of money; and what amount of labour is required to obtain that sum of money? It is useless to know that a man can obtain a certain quantity of wheat, clothing, fuel, or anything else, for a certain sum of money, unless we also know what work he must do to get that sum of money, or what means a man has of paying such a sum of money; and we have not sufficient facts to enable us to answer these questions.

There is, however, another way of arriving approximately at the comparative value of any given sum, at two periods; which, indeed, is a necessary step in all

calculations of this kind, but which alone gives us very little additional help. I refer to the quantity of fine gold or silver in any given coin at the two periods. This is an essential point, as it is obviously of no use knowing that wheat, for instance, was sold, at a certain time, at so many shillings a quarter, unless we also know whether, at that time, a shilling meant the same as a shilling now. The pound troy weight, or 12oz. of the metal of which English silver coins are

made, contains 11oz. 2dwts. of pure silver, and 18dwts. alloy. In the eighth year of the reign of Edward I., (A.D. 128) this pound-weight of silver was coined into twenty shillings. In A.D. 1816, and at present, the like quantity was coined into sixty-six shillings. The shilling of A.D. 1280 was, therefore, equal to about 3s. 34d. (say 3s. 3d.) of the present coin: that is to say, the shilling of the present day is worth less than one-third of the shilling of the time of Edward I.; and, on this basis, if we wish to convert the money of the thirteenth century into the money of the present day, we must multiply it by three and a quarter. But it is obvious that this calculation gives us no measure of the value of any article of produce, as compared with the power of purchasing it; and the conflicting opinions of different political economists, as to the multiplier to be made use of, convince me that at present we have not sufficient means for ascertaining the relation borne in the thirteenth century by a payment to the means of meeting it. We cannot say that, as compared with the present time, taxation was heavy or light, wages were high or low, oxen, sheep, or poultry were cheap or dear; all we can do is, to convert shillings of the thirteenth century into shillings of the nineteenth, and then compare the relation which the prices of various articles at any particular period bore to each other at that period, and to the prices of a list of articles, of apparent similarity, at the present period. It may perhaps, however, be allowable to say, as a result of the inquiries which have been made, and the opinions which have been given by various persons, on this subject, the multiplier which will, with approximate correctness, convert the money of Edward I. into a purchasing power of equal force at the present time, would be somewhere between 12 and 20. Thus, for example, £100 of money in the time of Edward I. would, all things considered, go as far in purchases of all kinds as £1,200 or £2,000 at present. Mr. William Longman.

DISCOVERIES AT ROME AND ATHENS. In a letter addressed to the Nation," M. Duchesnay gives an interesting account of the discoveries lately made in the environs of Rome, on the spot where Constantine defeated Maxentius, that is, near Cremera, outside the Porta del Popolo. On one of the hills of that locality, a villa, believed to have belonged to Calphurnia, Caesar's wife,

has this year been entirely exhumed. One of the conduit-pipes found on the spot bears the name of that lady. At an insignificant depth below the surface of the soil, a suite of rooms has been found, which must have been the ground-floor of the villa. The walls of one of these rooms are decorated with painted landscapes; one of them represents a grove of palm and orange-trees, with fruits and birds on the branches. The colours are perfectly well preserved, and as vivid as if they had been painted but a few days ago. The ceilings have fallen in, but from the fragments it is easy to perceive that they were decorated with aërial figures similar to those discovered at Pompeii. Glass and pottery have also been found on the spot; but the great object of attraction is a beautiful marble statue of Augustus, in his triumphal robes, open enough to reveal a richlysculptured breastplate, the subjects of which are Rome with a cornucopia, and the twins by her side; Apollo with his lyre, mounted on a hippogriff; Diana with a hart; Mars sheathing his sword; a trophy; and a triumphal car drawn by four horses, and preceded by winged figures of Victory. The feet of this statue are broken off, but not lost; one of them is flanked by a Cupid on a dolphin. The statue is two metres and a half in height, and bears evident traces of paint on its surface. The busts of Septimius Severus, his wife, and his son Geta, have also been found,

A letter just received in Paris, gives an account of the discovery near Athens, by pure accident, of some very interesting monuments. A small proprietor, amusing himself after the fashion of his kind in digging up his own potatoes, came on something hard. He tried to dig it up, but found it was a fixture. He cleared a part of it, and saw it was the wall of a building. He examined the wall, and found there was an inscription on it, which, as he could not read, gave him no great insight into his discovery. He, however, consulted his friends; further excavations were made; and, by a curious chain of circumstances, the digging of potatoes has opened to the eyes of the antiquarian world the Via Sacra which went from Athens to Eleusis. A long line of tombs, completely buried in sand, runs along both sides of this "sacred way," by which great Athenians used to be carried to their last home, and the fashionable world of Athens used to crowd to the fetes of Ceres.