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or flint, 28.9; protoxide of iron, 33.22; magnesia, 19.2; alumina, 5.22; lime, 1.64; oxide of nickel, .82; oxide of chromium, .7; cobalt and soda, a trace.

ELECTRICITY.

Ar the Electrical Society, on the 2nd inst., a paper was read from Mr. M. Roberts, describing an improved Galvanic Battery. The trough is a wooden box, divided into cells by means of circular disks of copper and zinc, in metallic connexion, fitted on a wooden axle, and half immersed in dilute acid. Between the copper and zinc disks, in each cell, a strip of flannel or cloth is extended from one end of the trough to the other, lightly rubbing on the sides of the contiguous disks or plates, which are turned slowly round, by means of a handle attached to the axle. He found the production of gas to be four times as rapid when the disks or plates are turned, than when not, owing to their constant clean surface, and from the increased galvanic energy acquired by the plates being exposed to the air in their revolution, one half of the surface being always so exposed. A battery of this kind is much less expensive than that of Daniell's.

M. Arago has proposed a plan for discharging clouds, in cases of storms, of the electric fluid which they contain, and thus preventing the frequent occurrence of hail storms, which are generally produced by two currents of clouds, charged with positive and negative electricity, crossing each other. It consists in an improvement upon Franklin's experiment of the kite, with which he obtained an electric spark from a cloud; and afterwards Dr. Romas, of Nerae, and Messrs. Lining and Charles, of the United States, produced electric flashes three and four feet in length. M. Arago recommends that a small balloon, properly secured, armed with metallic points, and communicating with the ground by a rope covered with metallic wire, like a harp-string, should be kept permanently floating in the air, at a considerable height over the spot which it is wished to preserve from the effects of lightning or hail; and he expects that by such an apparatus as this, a cloud might have its electric contents entirely drawn off, without any damage being caused, or that at least the intensity of a hail-storm would be greatly diminished. The experiment is so simple, that it is well deserving of a trial.

IMPORTANT CHEMICAL DISCOVERY.

ONE of the most valuable improvements in modern times has lately been achieved in the manufacture of soda from common salt, by the use of carbonate of ammonia, instead of the pestiferous method hitherto employed in

the production of that alkali. The inhabi tants residing in the vicinity of the sodamanufactories at Birmingham, Liverpool, Newcastle, Glasgow, &c., owe the inventors of this invaluable improvement a heavy debt of gratitude, as by this discovery they have put an end to the dreadful nuisance which the public have so long endured. The necessity of decomposing the chloride of sodium by sulphur no longer exists, the newly-discovered process being perfectly free from all noxious vapour. Another important advantage is also secured-namely, that the improved method can with little additional outlay be adapted to the manufactories at present in operation,

and the workmen who have hitherto been frequently thrown out of employment and subject to the loss of their wages, in consequence of the numerous indictments that have been laid against their masters for nuisances, will no longer be subjected to this evil. This process, when submitted to an eminent chemical lawyer for his opinion, was pronounced by him to be one of the most brilliant and ingenious discoveries in modern chemistry.- From a correspondent, in the Morning Chronicle.

EXPERIMENTAL SUBTERRANEOUS AND SUB

AQUEOUS EXPLOSIONS AT CHATHAM BY
THE VOLTAIC BATTERY.

FOR several months past the Royal Engineers, at Chatham, under Colonel Pasley, have been trying continual experiments in firing gunpowder by the voltaic battery, chiefly under water; and after many vicissitudes of partial success and of failure, they have at last succeeded in bringing this process to as much perfection as it seems capable of; that is, to as much certainty as the former methods of firing mines in dry soil. They have repeatedly fixed gunpowder at the distance of 500 feet, with their conducting wires either buried underground or led entirely under wa ter, excepting a few feet connected with the battery, which in their subaqueous explosions was in a boat on the Medway, the powder being lodged at the bottom of that river. In their subterraneous explosion they blew up a field-work; and in one of their subaqueous experiments they blew to pieces a vessel representing a wreck, the fragments of which being of fir timber came up to the surface of the Medway immediately after the column of water thrown up by the explosion. On Saturday April 6th, they applied their voltaic battery to the blasting of rock under water. Two very large and heavy pieces of hard sand-stone were each prepared with a hole three inches in diameter by a boter, after which a charge of three quarters of a pound of powder was put into each, and the upper part of the hole was tamped by pouring in small fragments of broken stone round a cone fixed over each charge, in a new and ingeni

ous manner, first suggested by Mr. Howe, clerk of works of the Royal Engineer Establishment, more than five years ago, which does not seem inferior in resistance to the common mode of tamping, but is much safer, and far more expeditious. The conducting wires were led from each charge to the battery, which was placed on the gun-wharf, whilst the stones thus prepared and loaded were lowered down from a crane to the bottom of the river opposite, where the water was 14 feet deep at the time. The first stone being of a compact form was blown to pieces, and the rope sling by which it had been lowered, and which had not been removed, was broken. The second stone being of a more irregular shape and much thinner, so that there was not sufficient resistance above and below the charge, was brought up by the crane after the explosion, which had only blown out the solid part of the stone below the bottom of the hole, apparently without injuring any other part of it. Another charge was, therefore, placed in the same hole, which was tamped both above and below in the mode before described, and the stone was then again let down to the bottom of the river; and after firing this second charge, on being hauled up by the crane, it was found to have been broken into three parts, one of which did not reach the surface, whilst the other two being still held together by the slings, after being raised nearly to the level of the wharf, separated from each other and fell to the bottom. One of these charges was contained in a tin cylinder fitted to the size of the hole; the two others in canvass bags of the same form, covered with waterproof composition. These last experiments have proved that the voltaic battery may succeed for blasting rock under water, as well as for blowing wrecks to pieces; and on the former supposition, the holes in the rock would be formed, and the charges placed, by means of the diving-bell.

water before it was fired, when the powder was still perfectly dry.

The voltaic battery used was of Professor Daniell's improved construction, which, from retaining its energy much longer than any former voltaic battery, he has named the constant voltaic battery, and which Colonel Pasley found to be much superior to the best of the former constructions, at least for the peculiar purpose of firing gunpowder, either under ground or under water.

ESTIMATION OF THE MARINER'S
COMPASS IN CHINA.

ALL the junks which are employed on although it does not appear to give the the ocean carry the mariner's compass, Chinese navigators confidence, as they never, if they can avoid it, steer boldly out to sea, but keep as much as possible within sight of land. The Chinese consider that they were the inventors of this inestimable little instrument, and it cannot be denied that they have had it in use for many centuries. According to Klaproth, the knowledge of this instrument was communicated to the Arabs by the Chinese, and introduced into Europe by the crusades. However much they may fail to rely on its virtues, they appear to be sufficiently aware of its powers. It is considered as a deity, and they treat it as they do the others, with great ceremonial. Pieces of scented ghos-stick are kept constantly burning around it, as in the ghos-houses; while sacrifices of the youngest flesh and the finest fruits are offered to it. Here, ignorance appears to be the parent of superstition; but it is to be hoped that a knowledge of the laws of nature may open their eyes to the wisdom and excellence of the works of the Creator.-Fan-Qui in China, by C. J. Downing, Esq.

SHIP-TIMBER.

Nothing can appear easier than to fire gun- ON THE PROCESS OF KYANISING powder under water, by the voltaic battery, as exhibited in a lecture-room or scientific institution; but the mode usually adopted on such occasions, of passing the conducting wires into the charge through a cork coated with sealing-wax, and of insulating the remaining length of each wire by inclosing it in small India rubber tubes, would be inadequate and inexpedient for practical purposes in a rapid tideway and in deep water. In Colonel Pasley's experiments at Chatham, corks and sealing-wax were rejected, the former as being too weak, the latter from being liable to crack: and India rubber or caoutchouc was also rejected as being far too expensive-instead of which a composition of pitch softened by bees'. wax or tallow was adopted, the remarkable efficiency of which was proved by keeping one of those experimental charges ten days under

Ir is to be hoped that we shall have no more tampering with dry-rot doctors and their nostrums for the preservation of her Majesty's ships. The steeping of large logs of timber in solutions of any kind is perfectly useless: the solution penetrates only skin deep, whereas the real dry rot commences at the centre, where the fibres, being the oldest, first give way, as is the case in standing trees. The only plausible and promising preservative of timber is the gas of the kreosote procured from the distillation of coal or vegetable tar, which, when driven off in the shape of gas, will penetrate every part of the largest logs, and render the wood almost as hard as iron; so hard, indeed, as not easily to be worked. It is understood that, in Belgium,

they are using it as blocks for the rail

roads.

The worm (Teredo navalis), as proved at Sheerness, will not touch it; while pieces of the same wood, steeped in corrosive sublimate, sulphureous acid, and other active solutions, were bored through and through. Let our ships be built of good sound English oak, as they formerly were, well seasoned under cover, and left on the stocks as long as they conveniently can be allowed, and we shall hear no more of dry rot, or wet either.-(Sir John Barrow's Life of Lord Anson, as quoted in the Mech. Mag., vol. xxx. p. 336.)

The Gatherer.

THE splendid present of the Schah of Persia. to her Majesty, consists of between 50 and 60 superb shawls, woven in the looms of Shiraz and Ispahan, exhibiting proofs of skill and taste with which the workmanship of Europe would, perhaps, strive in vain to compete. The borders in some exhibit, in all their defails, a triumphal procession; trains of camels and Arab steeds, sumptuously caparisoned; elephants carrying palanquins, musicians gathered in groups, and the countless attendants of many mighty chiefs, being all portrayed with equal fidelity and splendour. These striking and complicated objects are woven in the most exquisite colours, with perfect accuracy of outline, and presenting a combination of forms and hues, unrivalled for their brilliancy and beauty.

Rice paper is made by the Chinese from a plant composed almost wholly of cellular tissue, and is removed from the tree like the unrolling of papyrus.

M. Parrot, who was ordered by the Rus sian government to explore Armenia and Transcaucasia, asserts that Mount Ararat is of volcanic formation.

a

A lieutenant on board the Recherche, in speaking of the late melancholy Earthquake at Martinique, says, that on the morning of that dreadful visitation (the 11th of January last,) the ship was shaken in every part by shock that lasted forty minutes, and the masts bent like bamboos. A few seconds after, a species of vapour rose from the shore, escaping through the crevices of the soil, and then the houses of Fort Royal began to fall. Those on the beach formed clouds of dust, and in the midst of the chaos a frightful cry arose from the lips of thousands of unfortunate sufferers. All the crews of the vessels, amounting to 500 men, were ashore in ten minutes afterwards, and at the end of some hours, two hundred persons still living, were disengaged from the ruins, and by the evening, 400 corpses were found.-Athenæum.

The number of merchant vessels belonging to Austria at the end of 1838, was 498, with

a total of 122,844 tons; the number of steamers was 15, total 5,114 tons. Out of the 498 vessels, 155 were employed in trading to ports in the Adriatic, the Levant, and the Archipelago: 147 in the Black Sea, the Sea of Azof, and the Danube; 167 in the Mediterranean; 12 in the Atlantic; 4 in the Northern Seas and the Baltic, and 13 to America.

The Golden Eagle.-The stamping of this superb coin has commenced at the Mint of Philadelphia: it is 34 years since any of this coin was struck, the coinage ceasing in 1804.

The zoological collection of the Garden of Plants in Paris has just been enriched by the present of an immense tortoise from a gentleman at Havre. It is a native of the island of Ascension, and weighs 500lb. It is five feet in length and three and a half broad. It arrived at the gardens on Friday evening, and on the following day laid four eggs.

Advice. The wisest men easiest to hear

advice, least apt to give it Sir W. Temple.

Correcting Proofs.-Hazlett, speaking of Burke, says "I have been assured by a person who had the best means of knowing, that the Letter to a Noble Lord (the most rapid, impetuous, glowing, and sportive of all his works) was printed off, and the proof sent to him, and that it was returned to the printing office with so many alterations and passages interlined, that the compositors refused to correct it as it was, took the whole matter to pieces, and rent the copy." The Georgian Era' states, that there is an instance on record, of three volumes of corrections being written to one volume of proofs.

Falsehood.-A liar begins with making falsehood appear like truth, and ends with making truth appear like falsehood.-Shen

stone.

The Mind and the Imagination. The mind hath over the body that command which the

lord hath over a bondman; but the reason

hath over the imagination that command which a magistrate hath over a free citizen, who may also rule in his turn.-Bacon.

Titles. Titles make a greater distinction than is almost tolerable to a British spirit: they almost vary the species; yet, as they are oftentimes conferred, seem not so much the reward as the substitutes of merit. Shenstonë.

NOTICE.

Nos. 941 and 942 of THE MIRROR having been re-printat may now be had of all Booksellers.

The ARCANA of SCIENCE, for 1839, by a New Editor, a gentleman of, acknowledged scientific ability, will shortly be published.

LONDON: Printed and published by J. LIMBIRD, 143, Strand, (near Somerset House;) and sold by all Booksellers and Newsmen.-Agent in PARIS G.W.M. REYNOLDS, French, English, and Ane ican Library, 55, Rue Neuve St. Augustin. — In FRANCFORT, CHARLES JUGEL.

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"Early in the reign of Elizabeth," says Mr. Corner, in his account of the above seminary, in the Gentleman's Magazine, January, 1836, "when the foundation of public schools was promoted throughout the country, under the authority of the legislature, and the patronage of the crown, the parishioners of St. Saviour's, Southwark, set a noble example to their neighbours in the establishment of their admirable Free Grammar-School; and the inhabitants of the parish of St. Olave were not slow to follow so enlightened and benevolent a policy. St. Olave's School was set on foot in the year 1560, and constituted "The Free Grammar-School of Queen Elizabeth of the Parishioners of the parish of St. Olave, by letters patent issued in 1571."

It was intended to have built the grammar school nearly on the same spot as the old school, viz., on the south side of Duke-street, leading from Tooley-street to London-bridge; but unfortunately that ground being required for the London and Greenwich Railway Company, a fresh site was obliged to be found; and after a considerable delay, and with a view to satisfy the inhabitants of St. John's, who were desirous that the new school should be erected in or near that parish, and on that account, the present wretched site was unfortunately chosen; for doubtless one more uncongenial for a classical school,-which ought to be all quiet and retirement, could not possibly have been selected; and it is also grievous in the extreme to witness so much taste as the above buildings display, completely lost, by being united with

such vile associates.

We are indebted to Mr. James Field, the architect, for the accuracy of our view; for which kindness we beg thus publicly to tender him our warmest thanks.

In the maps of the Metropolis, 1765, it is called Barnaby, or Bermondsey-street: doubtless it took its name from two Saxon-words, signifying Bermund's isle," so called," says Aóλoyos Bailey," from the abbey erected in Southwark by Bermund, either Lord or Abbot of that place." Many useful and

instructive chapters might be written on the origin

of the names of streets in London.

For a view of this school, see Mirror, No. 761.

SOUTHWARK TRADESMEN'S TOKENS. (Engraved from the Originals in the possession of the Editor.)

ON the old St. Olave's Grammar-School, which was situate in Church Passage, Tooleystreet, being sold in 1830, and taken down to make the approaches to New London Bridge, many antiquities were found amidst the ruins; and among them, the Southwark Tradesmen's Tokens, represented on our first page.

It appears in history, that from and during the reign of Queen Elizabeth, to that of King Charles II., the tradesmen, victuallers in particular, and indeed all that pleased, coined small money or tokens, for the benefit and convenience of trade. This small money, halfpence and farthings, was also coined by the incorporation of cities and boroughs. It was struck for necessary change; the figure and devices being emblematical of the various trades. Every company, tradesman, or tradeswoman that issued this useful kind of specie, was obliged to take it again when brought to them; and, therefore, in cities and larger towns, where many sorts of them were current, a tradesman kept a sorting-box, into the partitions of which he put the money of the respective coiners; and at proper times, when he had a large quantity of any one person's money, he sent it to him, and got it changed into silver and in this manner they proceeded until the year 1672, when, King Charles the Second having struck a sufficient quantity of halfpence and farthings, for the intention and exigencies of commerce, the nummorum fumuli were superseded, and an end was put to these shifts and practices of the victuallers and shop-keepers, as being no longer either necessary or useful.

numerable Tradesmen's Tokens in general Some forty years since there were again incirculation, not only in the metropolis, but in all parts of the country; some of them were specimens of fine workmanship, and were made the vehicle by tradesmen of advertising their various professions; and also of perpetuating the stirring events of the times, and also been the means of preserving Views of giving the portraits of public men; they have Places, and Notices of Entertainments, which otherwise would have been lost. A complete series of them now would be very valuable; and indeed so eagerly were they sought after by collectors, that eight volumes of engra vings from them were published; and many cabinets made for them. They also formed a circulating medium, until the splen did new copper coinage of George III. from the foundry of Mr. Watt's, of Birmingham, gave the public a more wholesome and valuable national coinage: when they soon entirely disappeared; and are now only to be found but in the cabinets of the curious.

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