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.