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WONDERS OF ART.

THE BRITANNIA TUBULAR BRIDGE.

THIS is one of the most remarkable structures in the world, the design of the celebrated architect, Sir R. Stephenson. This bridge is on the line of the Chester and Holyhead Railway, crossing the Menai Straits, within sight of Telford's Chain Suspension Bridge. It is made of cast iron of a tubular form, in the tube of which the railway passes. Four of these span the Strait, and are supported by

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piles of masonry; that on the Anglesea side is 143 feet 6 inches high, and from the front to the end of the wing walls is 173 feet. These wing walls terminate in pedestals, on which repose colossal lions of Egyptian character. The Anglesea pier is 196 feet high, 55 feet wide, and 32 feet long. In the middle of the Strait is the Britannia Rock, from which the bridge derives its name; on this the Britannia pier is raised. It is equally distant from the Anglesea and Caernarvon piers, being 460 feet in the clear from each, and

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sustains the four ends of the four long tubes, which span the distance from shore to shore. There are two pairs of short and two of long tubes, the lengths of these pairs being 250 feet and 470 respectively. The Egyptian lions are 25 feet 6 inches long, 12 feet 6 inches high, 8 feet wide, and weigh 80 tons. Two thousand cubit feet of stone were required for each lion. The total quantity of stone in the bridge is 1,400,000 cubic feet. The weight of malleable iron in the tubes is 10,000 tons, of cast iron, 1,400 tons. The whole length of the entire bridge, measuring from the extreme front of the wing walls, is 1,833 feet, and its greatest elevation at Britannia pier, 240 feet above low-water mark. The total cost of the structure is £601,865.

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"As a matter of history," says the Times, "a chronological summary of the structure will be interesting. On June 30, 1845, the Bill sanctioning the construction of the Britannia Bridge was passed by Parliament. In July the preliminary experiments to determine the form of structure commenced; April 13, 1846, the first workmen were engaged on the bridge; April 21, the first stone of the Britannia tower was laid; June 13, 1847, the first vessels arrived with iron at the Straits; August 10, the first rivet was inserted; February 22, 1849, the Caernarvon and Anglesea towers completed; April, 1849, the pontoons were brought to bear; May 4, first tube was completed and platform cut away; June 20, first tube floated: June 22, last stone in Britannia tower laid; November 9, first tube deposited in permanent bed; December 4, second tube floated; February 7, 1850, second tube deposited on permanent bed; March 3, Caernarvon small tube lowered; March 5, first engine passed through tube, and last rivet inserted; March 18, single line of tube opened for public traffic; June 10, third tube of second line floated; July 11, third tube deposited; July 25, last tube floated; October 21, second line of tube opened for public traffic."

resting them at intervals in the centre of the sections. Another trial was a train of twenty-eight wagons and two locomotives, with 280 tons of coal, drawn into all four of the tubes, the deflections being carefully noted. These deflections, in every case, by means of a nice apparatus for the purpose, were ascertained to be exactly three fourths of an inch over the immense mass and area of iron. After an interesting rehearsal of these experimental ordeals, which occupied several hours, the train of 280 tons, with its two locomotives, was taken out about a mile distant from the tube, and then suddenly shot through it with the greatest attainable rapidity, and the result was very interesting, as determining a much-discussed question; it being found that the deflection at this immense velocity of the load was sensibly less, in the way of undulation or collapse, than when the load was allowed to remain at rest in the tube. The manner in which these results were registered and arrived at was by means of a new and curious contrivance, it being found that the tremor occasioned by trains in transit prevented these deflections from being accurately read by the ordinary spiritlevel. This contrivance consists in a large pipe containing water, laid along the lower cells of the tube, one end rising up within the tube at the centre, and the other end fixed against the stonework of the abutments of the bridge. Both extremities of this pipe are furnished with glass tubes and graduated scales, by which the relative levels of the water are easily ascertained. As the slightest leakage or evaporation over the ordinary thermometric expansion of the water would derange the level, while only half the actual deflection of the tube was registered at each end of the pipe, these disadvantages are obviated by the addition of a large reservoir of water in the interior of the tube, which is covered with oil and placed beside the graduated scale. This larger area exhibits the whole of the deflections at the abutment extremity, and the apparatus presents a perfect mirror of all the deflections of the great structure.

According to the resident engineers, who have watched minutely from day to day, all the developed peculiarities of the novel undertaking, many curious and in

Before the bridge was allowed to be used for the conveyance of passengers and merchandise, it was subjected to very severe tests. "The first and principal experiment consisted in passing two locomotive engines through the tube, and

teresting results have been produced. These gentlemen state that the heaviest gales through the Straits do not produce so much motion over the extent of either tube as the pressure against the side of the tube of ten men; and that the pressure of ten men, keeping time with the vibrations, produces an oscillation of 14 inch, the tube itself making 67 double vibrations per minute. The strongest gusts of wind that have swept up the channel during very stormy weather did not cause a vibration of more than a quarter of an inch. The broadside of a storm causes an oscillation of less than an inch; but when the two tubes are braced together by frames, which is now being done, these motions will be almost annihilated, and all apprehension from wind or weather, from their being secured together, will cease. The meteorological results, since the tubes have occupied their elevation, have materially differed from those that were observed when they lay along the Caernarvonshire coast. The action of the sun at midday, instead of bending them two or three inches, does not move them more than two or three eighths of an inch. The daily expansion and contraction of the tubes varies from half an inch to three inches, attaining either the maximum or minimum at about three o'clock A. M. and P. M. These and other interesting results, as indicating the safe working of the great machine, are read by means of self-registering thermometers that record the constant temperature, placed in mahogany cases, protected by plate-glass, and under lock and key. There is also a self-acting clock-work apparatus that elevates a shaft on a vertical plane, all the minutest motions of the tubes being delineated by an arm carrying a pencil, which is fixed to the tube. If a compass be held over any part of the bottom of the cells, the south pole is affected, and if held over the tops of the cells, the north pole is affected; and this effect is observable in all parts of the tube, whether at the centre or end, although their position is only about 10° W. of the magnetic meridian.

Some of the acoustic effects produced by the bridge are curious. The report of a pistol fired beneath it is repeated three or four times. The cells of the top and

bottom form excellent speaking tubes; and, by elevating the voice, persons may converse through the entire length of the bridge, more than 500 yards. If one end of the cells be closed they return a powerful echo; but, although a whisper is thus distinctly repeated, the loudest whistle does not appear capable of returning any echo.

ADVICE TO PIANISTS. ALWAYS insist on having your instrument purely tuned.

A player may cram his memory with finger passages; they all, in time, grow commonplace, and must be changed. Only where such facility serves higher ends, is it of any worth. Play nothing, as you grow older, which is merely fashionable. Time is precious. One must have a hundred human lives, if he would acquaint himself with all that is good. You must carry it so far that you can understand a piece of music upon paper. Strive to play easy pieces well and beautifully; it is better than to render harder pieces only indifferently well. You should sedulously practice scales and other finger exercises. But there are many persons who imagine they have accomplished everything when they have spent many hours each day for years in mere mechanical exercise. It is about as if one should busy himself daily with repeating the A-B-C as fast as possible, and always faster and faster. Use your time better.

Accustom yourself, even though you have but little voice, to sing at sight without the aid of an instrument. The sharpness of your hearing will continually improve by that means. But if you are the possessor of a rich voice, lose not a moment's time, but cultivate it, and consider it the fairest gift which Heaven has lent you. You must not only be able to play little pieces with the fingers; you must be able to hum them over without a piano. Sharpen your imagination so that you may fix in your mind not only the melody of a composition, but also the harmony belonging to it.

The cultivation of hearing is the most important matter. Take pains early to distinguish tones and keys by the ear. The bell, the window-pane, the cuckooask yourself what tones they each give out.

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Nor murmuring tribes from me derive
Th' ambrosial amber of the hive;
Yet leave this barren spot to me:
Spare, woodman, spare the beechen tree!

Thrice twenty summers I have seen The sky grow bright, the forest green; And many a wintry wind have stood In bloomless, fruitless solitude, Since childhood in my pleasant bower First spent its sweet and sportive hour, Since youthful lovers in my shade Their vows of truth and rapture made; And on my trunk's surviving fame Carved many a long-forgotten name. Oh! by the sighs of gentle sound, First breathed upon this sacred ground; By all that Love has whisper'd here, Or Beauty heard with ravish'd ear; As Love's own altar honour me: Spare, woodman, spare the beechen tree! CAMPBELL.

WATER.

"WATER! Water!" cries the bird, With his singing, gentle note; And the liquid cry is heard Pouring from the little throat, Water! water! clear and sweet! "To-weet! To-weet!"

"Water! Water!" roars the ox,

While it rushes at his side, Down among the mossy rocks Rippling with its crystal tide; Water! water! pure and true! "Moo! Moo!"

"Water! Water!" said the tree, With its branches spreading high; "Water! Water!" rustled he, For his leaves were very dry; Water! water! for the tree! Pure and free!

"Water! Water!" said the flower, Whispering with its perfumed breath "Let me have it in an hour,

Ere I thirsting droop in death!
Water, water, soft and stili,
Is my will!"

"Water! Water!" said the grain, With its yellow head on high; And the spreading, fertile plain, Ripening, join'd the swelling cry; Water for the grains of gold! Wealth untold!

Water! Water! sparkling, pure, Giveth Nature everywhereIf you drink it, I am sure

It will never prove a snare! Water is the thing for meYes! and thee!

Water! Water! young and old! Drink it, crystal-like and sweet! Never heed the tempter bold

Crush him underneath your feet! Water! Water! Youth for thee

Thee and me!

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A foot more light, a step more true,
Ne'er from the heath-flower dash'd the dew;
E'en the slight hare-bell raised his head
Elastic from her fairy tread. WALTER SCOTT.
Breaking hearts
Require a drapery to conceal their throbs
From cold inquiring eyes; and it must be
Ample and rich, that so their gaze may not
Explore what lies beneath. MRS. HEMANS.
In vain I strive to put her from my thoughts,
To drive her out with empire and revenge;
Still she comes back, like a retiring tide,
That ebbs awhile, but straight returns again,
And swells above the beach.
ROWE

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INTERESTING VARIETIES.

THREE times as many children die in the first year as in the second; a greater number indeed die in the first year than in the six succeeding

ones.

GERMAN physiologists affirm, that of twenty deaths of men between eighteen and twenty eight years of age, ten originate in the waste of the constitution induced by smoking.

By the mere action of the lungs of the inhabitants of Liverpool, a stratum of air sufficient to cover the entire surface of the town, to the depth of three feet, is daily rendered unfit for the purposes of respiration.

IT has been ascertained that the quantity of soap annually consumed in the metropolis is about 12,000 tons, which, at £50 per ton, costs £600,000 and of soda, for washing, about 3,000 tons, which at £10 per ton, costs £30,000. L all £630,000 a year.

THE quantity of water consumed daily in London is equal to the contents of a lake fifty acres in extent, and of a mean depth of three feet; this quantity is by no means proportionate to the great and growing wants of the population. According to the last returns, there were 70,000 houses without any supply whatever.

THE parliamentary investigations into the cause of shipwrecks, show that a very large proportion of the accidents at sea arise from intoxicating liquors being allowed on board the vessels. In the report, it appears that the ave rage annual loss to this country, by shipwrecks, is £2,836, 166, and we are within the truth when we state that two-thirds of this loss of property is the result of our drinking system.

MR. BROTHERTON made the following state ment in his place in the House of Commons, on the 22nd of January, 1847:-"Of twenty shillings expended in spirits the amount paid for labour was only eightpence; but if twenty shillings were laid out in articles of manufacture, from six shillings to ten shillings went into the pocket of the artizan.

FERMENTATION destroys part of the flour or meal. We find, in consequence, that a sack or 280lbs., which makes 360lbs, of bread, or 90 quartern loaves, by fermentation, gives 408lbs., or 102 quartern loaves, by effervescence. The loss by refining is still greater: a quarter of wheat, weighing 520lbs., or 65lbs. per bushel produces 512lbs. of meal; and these, after a course of screening, yield only 416lbs. of flour, -a diminution of 96lbs., or 18 per cent.

THE population of England and Wales is about 16,000,000, the annual waste of life 35,000, and the cases of unnecessary sickness little short of 1,000,000; so that of the total waste of life in England and Wales, somewhat less than onethird, or about two-sevenths, and the same proportion of cases of preventable sickness take place in London. The population of the United Kingdom is about 28,000,000, the annual waste of life upwards of 60,000! and the cases of unnecessary sickness, more than a million and s half! so that a sixth of the total waste of health and life takes place in the metropolis.

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