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SCIENCE.

THE BRITISH NAVY.-We clip the following CHAIN PLATING FOR SHIPS, - In the House of table from an interesting article on the British Lords, on the 4th of July, the Earl of Hardwicke, navy in the July number of the British Quarterly: adverting to the details of the recent conflict be"The strength of the Bristh navy, whether re- tween the Alabama and the Kearsarge, asked the garded absolutely or relatively, was never great-noble duke at the head of the admiralty, whether er than now. The catalogue of our iron ships will be best supplied by the following table, epitomized from a very recent parliamentary return:

ARMOR-PLATED SHIPS OF THE BRITISH NAVY,
MAY 2D, 1864.

Name.

AFLOAT.

£

Partially 868,813

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66

600

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249,064

35 4056 800 Wood Wholly 259,656
206,000
206,000
Partially 171,500

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35 4125 1009

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85 4047 1000

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Zealous.

20 3716 800

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Reserach

Enterprise..

4

4 1253 200
998

66

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160

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Royal Sovereign

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65,600
52,400

Whether

armor-
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his attention had been directed to the question of protecting ships of war by chain - armor. The subject was not a new one, for it had been discussed in a letter written in 1862 to the noble lord at the head of the government, by an ironmaster resident at Belfast, in which he drew attention to the important results which might be gained by suspending chains over a ship's side to act as a foil against shot.

The Duke of Somerset said the defense afforded by the chain-plating to the Kearsarge must have been very small, for it only extended over a space about thirty-six feet in length, and the chain was of the kind known as one and three quarter inch. 860,995 240,718 The firing from the Alabama could not have been 247,672 good, for this strip of plating was only struck 286,718 twice during the engagement; one of the shots 821,875 glanced off, and the other, which was the only one that hit the armor fairly, pierced it and lodged in the side of the vessel. At the same time, it was known that the Alabama entered upon the contest under great disadvantages, her powder being either damp or very dry, and the vessel herself in a very unfit state. Two or three years ago the admiralty made some experiments with chain-armor, and the result was that with a common 68-pounder and cast-iron shot it was knocked all to pieces, so that against steel projectiles it would afford no defense whatever. It did not at all follow that, as a make-shift, it would not be better than nothing, and at a long distance, as in this case, it had some advantages. But what the admiralty had to decide was: given a certain weight, how to apply it most effectively for the defense of a ship. (Hear.) Some time ago the noble earl opposite expressed a doubt whether 206,000 guns weighing six and a half tons each would not 278,400 285,400 be found too heavy for broadside purposes. He Partially 136,145 had since ascertained that the two 11-inch guns on board the Kearsarge, one before, the other abaft the mainmast, weighed each seven and three quarter fons. The real conclusions to be drawn from the conflict between the Kearsarge and Alabama were, that very powerful guns and very speedy vessels were required. The speed of the Kearsarge gave her great superiority over the Alabama, which, morever, was not built for fighting purposes, but mainly with a view to cruising. Experiments had shown conclusively that the continuous surface of armor-plate yielded great advantages over interrupted surface like bar-iron or chain-covering.-Saturday Review.

26 6621 1850 Iron Partially

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Bellerophon
Prince Albert
Royal Albert.
Lord Clyde
Lord Warden.
Pallas..
Favorite.
Viper...

35 4045 800 Wood

Vixen

24 4067 1000
24 467 1000

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6 2372 600

10 2186 400

64

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weary traveler should be thus unexpectedly and fully supplied. In the wilderness waters have literally broken out. Perhaps no more hopeless enterprise could be undertaken than to attempt to reclaim the great African Desert of Sahara, where no rain ever falls, and there are but occasional oases to give relief to the weary and fainting caravans that traverse it. Modern science, however, laughs at seeming impossibilities. Skillful engineers in the French army in Algiers propose to sink Artesian wells at different points, with strong confidence that thus water would be reached and forced to the surface. In 1860, five Artesian wells had been opened, around which, as vegetation thrives luxuriantly, thirty thousand palm-trees and one thousand fruit-trees were planted, and two thriving villages established. At the depth of a little over five hundred feet, an underground river or lake was struck, and from two of them live fish have been thrown up, showing that there was a large body of water underneath. The French government, by this means, hopes to make the route across the desert, to Timbuctoo, fertile, and fit for travelers, and thus to bring the whole overland travel and commerce through Algeria, which will be one of the greatest feats of modern scientific enterprise.

py the next place, followed by South America (Brazil mainly), the West Indies, and Africa.

It has been used for the manufacture of cloth more than two thousand years, being first known in India, then introduced into Greece and the countries of the Mediterranean. It is now found in all tropical latitudes, and adjacent temperate localities in the United States south of 35 deg. ; in the West Indies; in South America down to Peru; in the Pacific Isles; in Australia, Japan, India, and China, and in nearly all explored portions of Africa.

The United States census for 1850 gave the average product per acre in unginned cotton, by States, as follows:

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This statement shows the difference in soil, and the effects of wasteful culture in the older States; but it shows most conspicuously, also, the influence of climate, especially in the figures for South Carolina and Tennessee.-Report of Agricultural Department.

ARTIFICIAL IVORY.-The possibility of procuring a substitute for ebony and ivory has become an important question, now these materials command such extravagant prices. M. Ghoulston Ghislain has brought before the French Academy a substance which he asserts answers this purpose completely. He produced it by the following method: Take sixty per cent. of the powder of marine plants, fifteen per cent. of glue, and an equal quantity of coal tar; boil till thoroughly mixed; dry in an oven at a temperature of 300 deg. F. till it becomes plastic. The compound will assume the appearance of ivory by heating it in an aqueous solution of caustic potash, and letting it macerate for several hours in diluted sulphuric acid; after which subject it to the action of chlorine or chloride of lime, repeating the operation till it becomes perfectly white.

COTTON SUPPLY.-The annual meeting of the Manchester Cotton Supply Association took place at Manchester yesterday afternoon; Mr. John Cheetham, the president, took the chair. The report stated that the correspondence of the association from every quarter indicated unabated determination to develop to the utmost the resources of the various cotton-fields on which the absence of the American supplies had made us dependent, and the association had seized every opportunity to render all the practical assistance in their power. They had distributed seed to the amount of 2032 cwt., and had supplied 156 gins, three driving. wheels for working gins, 1000 gin-saws, and 150 ginbrushes, in Bombay, Java, Cape of Good Hope, Barbary, Morocco, Algiers, West Coast of Africa, Malta, Beyrout, West Indies, Turkey, Australia, South America, and other parts of the world. The chairman said the supply of cotton, while it was likely to fall short of the highest anticipations formed at the commencement of the year, was, he of the soaring lark, we may be sure that the entire POWER OF A BIRD'S SONG.-When we hear the song was happy to say, likely to exceed the lowest. Alluding to the partial failure in Egypt, owing to atmosphere between us and the bird is filled with the overflow of the Nile and other causes, he said pulses, or undulations, or waves, as they are often that we might expect a considerable increase next voice. This organ is a vibrating instrument, recalled, produced by the little songster's organ of year from what was heard of the direction of cap-sembling, in principle, the reed of a clarionet. Let ital to steam-pumps for irrigation and to plows. He was told that a manufacturer of steam-plows in the south of England had orders for a quantity for Egypt that would take him some years to complete. He expressed a wish that in all countries where they were desirous of rendering really good service in this direction that they should direct attention to improvement by using as much as possible American seed to grow from. He concluded by moving the adoption of the report. Mr. Edmund Ashworth seconded the report, and it was adopted unanimously.-Times, June 29th.

THE CULTURE OF COTTON.-Much the larger proportion of cotton grown is produced in this country. Seven eighths of the entire product of the world, it has been estimated, has been reached by our increased production. The East Indies occu

to a height of five hundred feet in the air. Beus suppose that we hear the song of a lark, elevated fore this is possible the bird must have agitated a sphere of air one thousand feet in diameter-that is to say, it must have communicated to seventeen thousand eight hundred and eighty-eight tons of air a motion sufficiently intense to be appreciated by our organs of hearing.-Tyndall's Glaciers of the Alps.

ROYAL GEOGRAPHICAL SOCIETY MEDALS.-At the anniversary meeting of the Royal Geographical Society for 1864, held at Burlington House, the Patron's, or Victoria, Gold Medal was presented to Captain Grant, for his journey from Zanzibar across Eastern Equatorial Africa to Egypt, in company with Captain Speke, and for his contribu tions to the work of that explorer. The Founder's

Gold Medal for the encouragement of Geograph- | Dunkirk. The light was supplied by a pile on Bunical Science was given to Baron C. von der Decken, for his two surveys of the lofty mountains of Kilimandjaro, which he is alleged to have ascertained to be capped with snow and to have an altitude of not less than twenty thousand feet. A testimonial has also been awarded to Mr. Gifford Palgrave, for his adventurous journey across Arabia. Sir Roderick Mrchison has been elected for the third time, annual president of the society.

CAUSE OF THE PERIODICAL RISING OF THE NILE. We learn from Barth's Travels (vol. ii. p. 437) that the waters of the Rivers Taro and Benuwe, in about the eighth degree of northern latitude, rise annually to the height of from forty to sixty feet above their lowest level, and preserve their highest level for forty days-namely, from the 20th of August to the end of September. Dr. Living stone tells us that the water of the Zambesi, at eighteen degrees south latitude, rises annually to a height of about twenty feet: so great is the mass of the annual tropical rains. From the same cause the Nile must overflow its banks when it is fed from a large large lake in the neighborhood of the equator, and is, in fact, the only outlet through which that lake rolls its superfluous waters to the Mediterranean,

sen's principle, composed of about fifty elements, and it succeeded tolerably well, but the employment of the pile was attended with much inconvenience. It was then determined to repeat the attempt with a magneto-electric machine. The new experiments tried at Dunkirk and Ostend had a double object1, to prove how the light produced by the machine would act under water; and, 2, to discover the effect the light wold produce on the fish. The first object was completely accomplished, and it is now the light they produce are applicable to all submademonstrated that magneto-electric machines and rine works. In fact, this light was constant at one hundred and eighty feet under water, and it extended over a large surface. The machine, nevertheless, was placed at a distance of more than three hundred feet from the regulator of the electric light. The glass sides of the lantern remained perfectly transparent, and the quantity of coal consumed was less than if it were in the open air.—Paris letter, June 28th.

WEDDOS OF CEYLON.-In the interior jungle regions of Ceylon a race exists, said to be descended from the earliest inhabitants of the island, driven into the forests by invaders about two thousand two hundred years ago. They are distinct from all other races of the island, though having communication in trade, exchanging wax, ivory, and dried venison, for salt and for arrow-root. They capture the only recently that they have begun to cultivate land, having lived entirely by the chase, and on wild fruits. Their language seems to be a dialect of the ancient Cingalese, mixed with Telugu. The women are kept secluded. In manners, customs, and religion, these Weddos seem to be of the lowest grade of human beings.-Proceedings of the Ethnological Society.

Journal contains the last of a series of articles by
FALLING STARS.-The July number of Silliman's
H. A. Newton on the “ November Star-shower."

ANALYSIS OF NILE WATER.-Professor Voelcker has analyzed specimens of Nile-water sent to him from Egypt, with a view to ascertain the causes of the re-game by bow and arrow, having no firearms. It is markable fertilizing effects which that water produces by its annual inundations, and also at what time during the flood those effects are most valuable. At the beginning of the flood, the water contains forty grains of suspended and soluble matter to the gallon; at the height of the flood, when the water is of a bright, almost blood-red color, the solid matter amounts to eighty-seven grains to the gallon. The red color is due to finely-divided oxide of iron, with which clay, fine sand, and organic matters are intermingled. It is chiefly the suspended matter which produces such astonishing effects on vegetation; and the organic matter contained in one thousand gallons is stated by Professor Voelcker to be capable, when deposited on the land, of genera ting three hundred pounds of ammonia. "From this," he says, "no surprise will be felt at the results practically obtained in the irrigated districts of Egypt." He remarks further, that "his object in relating some of the details which were brought to light in the course of his examination of Nile-water, is to direct the attention of English farmers to the benefits which are in most cases likely to result from a good system of irrigation."

THE FLORA OF AUSTRALIA.-Dr. Murray, who accompanied Mr. Howitt's expedition as medical officer, has brought back specimens of timber representing seventeen species of trees, the most peculiar of which have received the name of the cork-tree and the orange-tree. The fruit of the latter in outward appearance is not unlike a small orange, but it has a pungent flavor, which renders it disagreeable to Europeans, being something between a watermelon and cayenne pepper. The collection of timber, made with great labor, has been sent to Dr. Muller for examination.

FISHING BY ELECTRIC LIGHT.-A first attempt was made to fish by electric light a short time since at

In these articles Prof. Newton has traced the hisord of its appearance in A. D. 902. He predicts tory of the startling phenomenon from the first recanother great shower in 1866.

-It has been suggested by Dr. Desmartis, of Bordeaux, France, that the venom of different reptiles, properly administered, like other vegetable and mineral poisons, might be of some service in medicine. In India, birds stung by certain spiders will remain in a state of apparent death for several hours and then return to life again. In this country, the savages at the far West and Southwest, who are in possession of the terrible wooral or curare poison, into which they dip their arrows, know how to graduate the dose so as to benumb the victim, if they do not choose to kill it. Why, then, might not medical men, by judicious inoculation of venomous substan ces, obtain good effects from the peculiar action of each, as in administering arsenic, prussic acid, or strychnine?

-Sir John Herschel, in an article in the Quarter ly Journal of Science, throws out the suggestion whether the original exciting cause of solar spots may not be found in the circulation of an elliptic ring of planetary matter, in a state of division sufficiently minute to elude telescopic vision.

-Lobsters, says Dr. Buckland, if left on the

rocks, never go back to the water of their own ac- | cord; they wait till it comes to them. This peculiarity was observed after a land-slide on the coast of Dorsetshire, England, which by its great weight forced up a portion of the bottom of the sea. On this suddenly elevated bit of ground there happened to be several lobsters, who doubtless thought the low tide had taken place with uncommon celerity, and that it would return again. Anyhow, the foolish creatures waited for the tide to come up and cover them. Of course it never did come up again; they remained in their places and died there, although the water was in many instances only a few feet from their noses. They had not the sense to tumble into it and save their lives.

-A certain number of Europeans marry Indian wives, and the children of the two races are known as Eurasians, or half-castes, and amount to considerable numbers. At the census of 1837 they exceeded the English in the city of Calcutta. In 1861 the Europeans in all India consisted of eighty-four thousand and eighty-three military, twenty-five thousand five hundred and fifty-six civilians, and nineteen thousand three hundred and six women and chil- | dren.

2690. The instrument employed in this calculation is the thermo-electrical pile. The figures are lower than when the determination is made by the air pyrometer.

-A species of Ailantus, not the silkworm Ailantus, but the rhus verniz, yields the Japan varnish. It is cultivated in Japan and China, and could doubtless be raised to any extent in this country. The varnish is procured by making an incision in the trunk in the same way that is practiced in gathering pitch from the pine. The yield is said to be very large, and there is every indication that the cultivation of the tree would be profitable.

-The entire population of France is 34,900,000. Of these 14,300,000 are engaged in agriculture; 1,300,000 in manufactures on a large scale; 4,700,000 in a small way. The members of the liberal professions number 2,268,000; of domestics, nearly a million. Of the two sexes employed as above, those of the male sex, beginning with the agriculturist, number, under their respective heads just designated, 7,770,000, 8,000,000, 3,000,000, 1,500,000. At this rate there are upward of nine millions of females actively employed in the ways specified. Of this number, 6,500,000 are engaged in agriculture, as owners of the land, or in still larger numbers as tillers of the soil. The women occupied in the liberal professions amount to 760,000. There are 26,758 physicians and apothecaries, and 12,666 sages femmes, or midwives. The proportion of the two sexes engaged in domestic service are 287,730 men and 618,936 women.

-A new fishing lamp has been invented, which consists principally of a lantern, air-tight and watertight, having a double roof to rarefy the air, from which it is conveyed by pipes to the foot of the burner. This air is supplied by means of a flexible tube, and a similar tube is fitted to the roof to carry off the smoke and consumed air. It may be constructed for oil or gas. It can be let down into the -There are in England and Wales 44,695 lunawater twelve feet or more to allure the fish, which tics under care, in public and private institutions. are readily attracted by the glare of the light, and The commissioners in lunacy report that it is largewhich almost insures success. It may also be usedly increasing of late years. with advantage for the examination of submerged ships.

-At a recent meeting of the British Ethnological Society it is said there were placed "casts of the skull of an individual at different periods of adult life to show the changes" produced in ten years. It is on the same principle, we suppose, that two skulls of Dean Swift are preserved in Ireland, one when he was a boy and the other when he was

a man.

It has been satisfactorily ascertained by actual experiment that the surplus heat in the steam is not sufficient to evaporate enough water to fill its own volume with saturated steam and thus keep up the pressure, much less to increase it so greatly as to produce an explosion. The theory of boiler explosions from the mixing of water with super- -In the criminal prisons of England the inmates heated steam may then be regarded as settled. get three hundred and fifty ounces of food each per -In 1834 ten thousand tons of slate were ship-week while undergoing the punishment of hard ped from Portmadoc, in Wales; in 1863, seventy- labor. If stinted in food they are attacked with six thousand tons. This is from the district known diarrhoea and dysentery. as the Vale of Festiniog, and the shipments from Bangor and Caernarvon have increased in almost an equal ratio. The demand is so brisk at present for good slate that the buyers, as a rule, have to wait about twelve months before their orders are executed, and there is no doubt that double the yield of the quarries could be easily disposed of,

-The Russian government have ordered two hundred and twenty guns of 8-inch, 9-inch, and 11inch bore, all rifled muzzle-loaders, together with a number of steel shot and adjusting cylinders for loading. The value of the contract will be about $3,000,000. The 11-inch gun will weigh about twenty-seven and a half tons, and costs $30,000. The extreme length is seventeen feet two inches. The diameter at the reënforce is forty-seven and a half inches. The whole gun is of cast steel, and the barrel alone will require an ingot of forty tons in weight, upon which cast-steel rings of a peculiar form are shrunk.

-Metals boil at the following tempreatures, Fahrenheit: Cadmium at 1328; zinc, 1688; silver, 1681; gold, 1879; palladium, 2517; platinum

-In France no less than 500,000,000 of francs are annually expended in the purchase of guano, bones, phosphate of lime, and other artificial manures, but, as in America, great frauds are committed by adulteration. It is also said that the oxalic acid contained in guano, hitherto overlooked, is an ingredient of prime importance.

-Prof. J. D. Whitney, who is making the geological survey of California, gives glowing descriptions of its mountain scenery. High up in the Sierra he discovered views wonderfully grand. He says, "We were camped for a fortnight at an elevation of about 10,000 feet, surrounded by hundreds of unnamed peaks, rising from 11,000 to 13,000 feet in height." The latter is the height of the Jungfrau in Switzerland. Mont Blanc is about 16,000 feet.

-Strange as it may appear, a ball of a ton weight and another of an ounce weight falling from any height will reach the ground at the same time.

-The productive capital in British railways is estimated at two thousand millions of dollars.

-The harbor of Sebastopol is nearly cleared of the ships sunk there during the Crimean war.

ART.

THE two pictures which attracted the most attention at the exhibition of the Royal Academy of Arts (London) this year were Herbert's fresco, or rather "water-glass painting," of Moses bringing the two Tables of the Law down Mount Sinai. The London Quarterly says of this: "It is a very grand work, well deserving all the praise that has been so freely lavished upon it. The scene is bare and desolate. The parched hills, burnt to a kind of yellow brown, with scarcely a shrub upon them, rise abruptly to the right. A blue haze, the result of the intense heat, lies in the valley; in which may be discerned the countless host of the Israelites. The face of Moses, as he comes down from the Mount, expresses, so far as we could read it, the abstraction and awe of a man who has been speaking face to face' with God, 'as a man speaketh unto his friend.' He does not see the wonder-stricken Israelites standing ready to receive him. The glories in which he has so recently been wrapt, still overwhelm him, as his soul travels down the ages, watching the influence of the Law on mankind. A white halo surrounds his head, and two rays shoot upward from the forehead. The tables of stone rest in his girdle, and are borne under each arm; the prophet, out of respect, forbearing to carry them in his hands. The two groups to the left and right are admirably disposed. The one to the left is headed by Aaron, who waits to receive Moses. Behind him stand Joshua and the other elders. We can not ourselves speak from experience of the amount of truthfulness and fidelity with which the local peculiarities of climate and dress are reproduced. Those, however, who have visited the East, are loud in their praises. The picture covers the whole upper portion of one side of a room, the base being cut in two by a doorway which is supposed to have some mystical meaning that we could not catch. The painting, and needful preliminary studies, occupied six years; and the rate of remuneration paid was three hundred and fifty pounds a year. Few persons will consider this an adequate return for one of the noblest works of art ever executed in this country, or regret that the House of Commons has expressed a very decided opinion on the subject."

The other picture is Sir Edwin Landseer's Man Proposes, God Disposes. The same authority thus

sketches it:

"A dreary ice-floe, scarce flushed with the rays of the setting sun, surrounded by the shadowy, unreal, half-transparent forms of the icebergs that,

'Mast high, come sailing by, As green as emerald."

a broken spar, and the remains of a boat in which human bones are discernible; a discolored Unionjack, a telescope, and a torn pocket-book; these, and two polar bears, one straining with all his force to tear the flag that has probably been a sailor's shroud, the other crunching a bone, and closing his eyes with a voluptuousness that is ghastly and horrible to witness; these, we say, form a picture which is nothing less than awful.

We are carried back to the time when brave men, full of heart and hope, started on their exploring expedition. We see their ship caught in the deadly embraces of the ice, and locked there while the long days grow into weeks, and the crawling weeks into laggard years. We live in thought through the terrible time, when, provisions beginning to fail, the men lose even that hope deferred which maketh the heart sick, and lay them down to die. And then comes the end; and their remains form a treasure-trove for these horrible bears. We can scarcely wonder that before such a picture the crowd should often be thin. This is no scene for the light hearts of holiday-making spectators. The skeleton at the Egyptian feasts could have cast no gloomier shadow.'

"Landseer's other pictures are a Piper and Pair of Nut-crackers—squirrels, as exquisitely graceful and pretty as the other is sublime; and two less important works. Besides these there was at the British Institution a fine portrait of two big dogs, and of some dead game, under the title of Wellbred Sitters that never say they are bored. This was one of the few redeeming features of an otherwise very discreditable exhibition; and as we have mentioned the British Institution, we may as well utter our grievances. It seems to get worse and worse year by year. Whether this degeneracy be due, as some artists would wish us to suppose, to a 'lay element' in the council, we can not say. Certain it is that the average merit of the paintings exhibited this year is singularly low."

"The

LEONARDO DA VINCI.-A letter from Italy, in a recent number of the Athenæum, says: prophecy that the present generation would be the last privileged to see even traces of the once glorious picture of The Last Supper, by Leonardo da Vinci, is unfortunately borne out by the state of that work. A more complete wreck can not well be conceived-so complete that it is now almost impossible to distinguish even the outline of the principal figures. This picture may be cited as one of the most remarkable instances of the perishable nature of oil colors. It was finished about 1498. In 1540 one half is said to have nearly disappeared, and ten years later nothing but the outline remained. How artists undertook to restore it, and what ruin they wrought, is well known. Very instructive, though not a little vexatious, is the fact that while this oil picture has disappeared, the large fresco of the Crucifixion, by Montorfano, executed in 1405, on the wall opposite The Last Supper, is in good condition; and we have many examples of admirably-preserved frescoes which date many centuries back."

IN the Exposition of pictures now open in the Palais de l'Industrie at Paris-an exposition perfectly bewildering, from the prodigious number of paintings hung on the walls-there is one large room exclusively for the rejected; and a very instructive room it is for those who wish to study the absurdities into which eccentricity, self-conceit, and ignorance will lead artists, so-called. This plan of

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