Science and Arts.

Colonist, Issue 8, 17 November 1857, Page 4

Science and Arts.

THE MONTH. (From .Chamber*? Journal, of August 1, 1857.) One of the chief scientific incidents of the past month was the ' Greenwich visitation,' as it is called—that is, the annual inspection of the Greenwich Observatory by the Board of Visitors, most of whom go down, a comfortable party, in the Admiralty barge, and dine together after their official business is over. The Astronomer Royal, in his Report on what has been done since the visit of 1856. tells them that the work of the observatory is progressing satisfactorily—that the new dome for a new class of equatorial observations will be completed this summer—that suspending the quicksilver trough of the reflex zenith tube by straps of vulcanised caoutchouc ' has been perfectly successful; the tremors are absolutely destroyed, and the star has been observed at all hours of the night and day.' And as regards the transmission of time by telegraph f ' Five clocks are in sympathetic movement in the Observatory—one at the Hospital Schools, and one in the North Kent Station at London Bridge. That for signals has received this slight alteration, that the pull of the Time-ball Detent now alters thf* connections of four triplets of spring. Of these, one controls the communications with the Electric Telegraph Company's office at Lothbury, by which hourly signals are sent on various railways; the time-balls at the Strand, Cornhill, and Liverpool are dropped, and the Post-office clock in Lombard-street is regulated. A second affects the communications with the - South-Eastern Railway station, by which hourly signals are sent on various lines in Kent, and the time-ball at Deal is dropped, and returns its signal to acquaint us with its successful drop. The third and fourth are reserved for the prospective wants of the royal dockyards; they communicate with the Admiralty wire of the British Telegraph.' It is probable that a time-ball will be erected at Devonport, the possibility of dropping such a ball by a flash from Greenwich having already been demonstrated. The Astronomer Royal still, as last year, refers to certain mysterious changes of level and direction of one of the instruments, one occurring with changes of temperature, the other at the equinoxes, and he still imagines some movement of the earth itself to be the cause of these remarkable phenomena. . There is to be a better education for ! officers in the army. No more getting commissions by favor; no more scandals about silly ensigns : but real practical ability and thorough knowledge of military science, are to be the rule. Above all, we want compe ent officers in India. A new magnetic survey of the British Islands is being made, whereby to discover and determine * what changes have taken place in the phenomena of terrestrial magnetism since the former survey by General Sabine in 1827. Mr. Welsh, of the Kew Observatory, conducts the observations in Scotland, Sir James Ross in England,'and, the Rev. Dr. Lloyd in Ireland; names which are a sufficient guarantee that the work will be well done. When done, there will be valuable data for Professor Hansten of Christiana, who has been for some time engaged on a theory of terrestrial magnetism derived from actual observation. About a year ago, he wrote to the Astronomer Royal, stating that the dip, as recorded at Greenwich, was much more in amount than, according to theory, it ought to be. The Greenwich dipping-needle was thereupon examined, and found to be extremely defective, depriving observations made with it of their value. It was at once rectified, with the effect of showing the dip to be the same as inferred by Professor Hansten. Specimens of sheet-iron have been laid before the Franklin Institute at Philadelphia, described as ' gum elastic coated and impregnated with iron,' .which is said to be better for roofing purposes than any other kind hitherto invented. No galvanic action takes place between the iron and the coating; hence disturbing influences of that kind are avoided. Sir Benjamin Hall has confessed before the House of Commons that the galvanised iron roof of the great Westminster Palace is beginning to show signs of rust. It might be worth inquiring whether the gum elastic coating and impregnation would afford the desired protection. We hear that the iron trade is so good in Wales, that new furnaces are being built at Dowlais, by which the manufacture will be doubled, hundreds of tons of bars rolled every week, and additional employment afforded. Man}' a visitor has gone down to the Isle of Dogs to look at the Great Eastern, without at the same time noticing thirty ' hopper barges,' built of iron, for dredging the Danube, in accordance with the terms of the treaty recently made with discomfited Russia. They are constructed with trap-doors at the bottom, for the discharge in deep water of the sand and gravel raised from the shoals. And this reminds us that the Netherlands Land Company have just reclaimed seventeen hundred acres of land, which, with the former reclamation, makes a total of nearly | three thousand. Their operations are carried on in the shallow channel which separates South Beveland from the mainland in the estuary of the Scheldt. And there is talk of reclamation at the mouth of the Mersey, as may be seen in a Report just published by Mr. George Rennie, the engineer. The project is, to build a breakwater out from Rock Point, on the Cheshire shore, across the shoals to a distance of three miles, the end to finish with a lighthouse. „, By the protection of this breakwater, it is estimated that from 30,000 to 40,000 "acres of land will be won from the sea.. Then, on the Lancashire side, a seawalHs to be built of the same length, and behind that there will be a saving of 2000 acres: hence the value of land is no unimportant item in calculating the result. The

form of the wall and of the breakwater will ,be such as to make a trumpet-mouth to the river, whereby the navigation will be greatly facilitated, and ample protection will be given to the North Docks at Liverpool, which now are scarcely accessible in blowing weather. And besides, wrecks will be prevented, and the cost of steamtugs saved, which is also no unimportant item in a port entered every year by 40,000 ships, amounting in gross burden to 4,000,000 tons. What has been done, and is still being done at Portland and Holyhead, shews how easy it is to build a break water far out to sea; and we should like to see the project carried out. Liverpool so completely outshines London in all that belongs to her river, that it is about time the metropolis should be shamed into doing something to remove the reproach from the Thames.. Among proceedings in geology, we find something interesting in the researches of Baron de Beust, chief director of the miningdepartment in Saxony, who has been led to the conclusion that minerals are diffused throughout his native country, and Europe generalty, according to certain simple laws. He shews that the porphyry veins of Saxony run in lines corresponding to the direction of the mountain«ranges; and wherever porphyry is found, it is an indication of the presence of useful minerals. Taking Europe at large, he finds three principal metalliferous zones; the first, commencing in Bessarabia, runs through Hungary, Saxony, the Hartz, and across the Channel to the lead districts of Derbyshire and Cumberland; the second begins near Lisbon, and ends in Transylvania; the third, 400 miles in width, begins in the north-west of Spain, traverses the continent to Brittany, from thence to the smaller Channel Islands, touches South Belgium, and intersects the first zone. The tin of Saxony lies in the same line, as produced on the map, and runs from north-west Spain to Limoges; and ' a line drawn through the quicksilver deposits of Spain and Tuscany, if lengthened, will pass through Idria, and end in the veins of mercurial grey copper in Upper Hungary! Insstructive facts these for mineralogists! Endeavours have already been made to turn them to account. Mines long neglected in Bohemia are to be reworked, for with improved knowledge, geologists believe them to contain much undiscovered mineral wealth. That certain deposits take certain lines through the earth, has been for some time known. Haidinger showed, in 1849, that whenever boracic acid is found either free or combined with the rock, all the places lie on a line running north and south—from the Lipari Isles to Arendal in Norway.. From the latter place, a branch shoots off to the west, and terminates in Salisbury Crag, Edinburgh. Other lines, which have been partially traced, favour the belief that extraordinary mineral deposits will one day be discovered in the Caucasus. It is a remarkable instance of commercial enterprise, that auriferous quartz is now brought from Virginia to Frodsham, in Cheshire, where it is calcined and crushed, and the gold is extracted at' a profit, even should the yield be not more than an ounce and a half of gold to a ton of quartz.

In Paris, two ingenious Frenchmen have made a successful attempt to improve water-lenses. They have overcome the difficulties which have hitherto caused failure, and produce lenses, as we are told, which 'have the purity and perfection, nearly, without the cost of lenses of solid glassy' This success is likely to prove beneficial in more ways than one; for a water-lens properly illuminated will send its light to a distance of ten or twelve miles —the very thing, as it would seem, for railway signals, and for ships navigating the Channel.

A desideratum long sought for has now been achieved —thatis, a means of perfectly cleaning articles of silver without injury to the metal. It is the discovery of Professor Bottger, a German. Take a glass or glazed vessel sufficiently large for the purpose; fill it with a strong solution of borax or of caustic potash; drop it into an inner vessel made of zinc,. and pierced with holes as a seive. Then take your silver, plunge it into the liquid, moving it up and down, being careful that at each plunge it comes in contact with the sine. The effect is magical ; for under the combined action of the solution and of the electricity evolved by the contact of the two metals, the silver, loses all is dirt and discolorations, and becomes as bright as when first manufactured. Should it not be convenient to use the inner vessel of zinc, the cleansing may be accomplished by sinking the silver in the solution and stirring it about with a small rod of zinc. It is essential to success that the two metals touch each other frequently.