memorial of the mournful march of the captive Hebrews. It is, we think, a very striking circumstance, that these countries should even now retain such unchanged lineaments of their ancient history. Time seems to linger, or move slowly on; as if the wheels of nature stood still, and paused at the mournful sight of departed grandeur and buried magnificence—BABYLON in ruins! 'MENE!—GOD hath numbered thy kingdom, and finished it!' Mr. Rich has given us a sketch of a spade copied from a Babylonian brick found near El Kasr, and detached from a mass of ruin, in all probability, on the very site of Nebuchadnezzar's pensile gardens; and he remarks, that it is almost a fac simile of the spade used at this very day in Chaldea."

SPIRIT OF DISCOVERY.

Heating with Hot Water.

Mr. A.M. Perkins has communicated to the Gardeners' Magazine the details of his plan for heating hot-houses by the circulation of hot water in hermetically sealed tubes of small diameter. Upon the economy of the plan, Mr. Loudon observes:—"With respect to the power of the one-inch tubes, it has been demonstrated by a mathematician and chemist of the very first authority, that as much will be effected by one of Mr. Perkins's one-inch tubes, heated to 300° as by one of the three-inch tubes, employed in any of the ordinary modes of heating by hot water when heated to 180°." A second advantage of Mr. Perkins's mode for hot-houses, is the small space which the pipes occupy. A third advantage is, that the water may be circulated without regard to whether the tubes are below or above the level of the fire-place. "But, however favourable this plan may be for heating hot-houses, the advantage for that class of structures are as nothing compared to those which it offers for heating dwelling-houses and all kinds of manufactories. This will be understood at once, when it is stated that the water may be circulated under ordinary circumstances of attention to the fire, at from 300° to 600°; and, with extraordinary strength of pipe, and application of fuel to a still higher degree. It is found that 400° will roast meat. The workmen in the bank-note printing-office of Messrs. Perkins and Bacon have dressed a beefsteak at the further extremity of the pipe of hot water used for heating the steel plates; and Mr. Perkins is constructing for himself an oven for roasting by water. It is easy to see, that, in a very short time, this will lead to extraordinary and most beneficial changes in domestic arrangements; and that if we could get rid of our prejudices in favour of open fires, the smoky atmospheres of our great towns would be got rid of at the same time. Water at 500°, or, at least, water at 300°, for the purposes of cookery, and for heating reserve cisterns of cold water, or masses of metal or masonry, for various domestic purposes, including warming rooms, heating baths, laundries, &c. may, at no distant time, be circulated by companies, in the same manner as gas; and, in London, instead of one fire for every room, as at present, there may be only one in a parish, or in every square of an acre in area."

A Marine Railway

for the purpose of conveying vessels overland, has been projected by Mr. Henry Fairbairn, in the United Service Journal for May, 1832. The vessels are to be raised from the sea by machinery, placed in slips and dragged along the railway by locomotive steam-engines. The same author proposes to connect Ireland with Scotland, by means of a bank between Portpatrick and Donaghadee; and England with France, by means of a chain bridge, causeway, or tunnel, from Dover to Calais. Over all the lines of marine railways he proposes to form suspension railways, resting upon arches, in the manner of Mr. Dick's, for the conveyance of passengers, mails, and merchandise.

Silk from Spiders.

At the last Anniversary of the Society of Arts, the Silver Isis Medal was presented to Mr. D.B. Rolt for obtaining Silk from the Garden Spider. We find the details in the volume of the Society's Transactions lately published.

"The subject of Mr. Rolt's experiments has been the garden spider, Aranea diadema, the webs of which, in autumn, are so conspicuous on the surface of shrubs and in other similar situations. On allowing one of these animals to crawl over his hand, he found that it drew a thread with it wherever it went: he likewise, without any difficulty, wound some of this thread over his hand, finding that the spider continued spinning while the thread was winding up.

"On this hint, he connected a small reel with the steam-engine of the factory in which he is occupied, and putting it in motion, at the rate of 150 feet per minute, found that the spider would thus continue to afford an unbroken thread during from three to five minutes. The specimen of this silk, which accompanies Mr. Rolt's communication, was wound off from twenty-four spiders in about two hours. Mr. R. estimates its length at 18,000 feet; its colour is white, and its lustre is brilliant, and completely metallic, owing, probably, to its great opacity. No attempt has been made by him to combine two or more filaments into one by winding, nor, of course, to form it into thread by throwing.

"The thread of the garden spider is so much finer than that of the silk-worm, that the united strength of five of the former is, according to Mr. Rolt, equal only to one of the latter; and, assuming that the weight is in proportion to the strength, and that a spider will yield twice a-year a thread 750 feet long, while that produced by a single silk-worm is 1,900 feet, it follows that the produce of one silk-worm is equal to that of 6.3 spiders. Now, as on an average it takes about 3,500 silk-worms to produce a pound of silk, it would take about 22,000 spiders to produce an equal quantity. Besides, spiders are not so easily confined as silk-worms, and whenever two come in contact, a battle ensues, which ends in the destruction of the weaker one. Spiders kept for silk must, therefore, be each in separate dens or cells; and the apparatus contrived by Mr. Rolt for this purpose, although very ingenious and well adapted to carry on a course of experiments with a hundred or two, would manifestly be wholly inapplicable to any purpose of commercial utility. Mr Rolt has, however, made some interesting additions to the history of the garden spider, and has obtained the silk in its natural state, exhibiting all its peculiar lustre; his method, likewise, of winding the silk directly from the animal is, to say the least of it, effectual and ingenious."

It should be added that "the Society are of opinion that it will never be possible to employ spiders' silk, beautiful as it is, in any profitable manufacture; but have thought proper to confer a reward on this gentleman for his communication, as forming an interesting addition to the natural history of the spider."

Medicinal Employment of Holly Leaves.

Dr. Rousseau has obtained from the Medico-Botanical Society of London its silver Medal, for an essay on the effects of holly leaves in fever: he has cured several intermittent fevers by the remedy, whose alkali he calls Ilicine.—Gazette of Health.

Tobacco no security against Cholera.

M. Chevalier proved, from documents, that the assertion made on a former evening, that tobacco was a preservative against cholera, was erroneous. He stated that twenty-seven mechanics employed in the tobacco manufactories had died of the disease.—Ibid.

Prussic Acid a Poison to Vegetables.

The sensitive plant, when exposed to the vapour of prussic acid, instantly closes its leaves. The same plant, as well as other tender plants, such as the garden pea and kidney bean, when subject to the influence of this acid, quickly wither and die, and the laurel-water has the same effect upon them. It appears also that plants