AND OF THE PHYSICAL SCIENCES. 



35 



near Enderby's Land discovered in 1832, or by Captain Weddell's furthest 

 reach, about 73°, in 1823. It is between Sabrina Land and Balleny Isle, 

 to the northward, and in about 50° and E. long. 140°, that it is expected 

 the south magnetic pole will be found. Strange if he who discovered 

 either that of the north, or so near an approach to it, as Captain James 

 Ross did, should also ascertain this long sought phenomenon. We had 

 forgotten to mention, that the vessels are constructed on the plan which 

 divides them into three compartments ; so that either extremity or the 

 middle might be stove in, and yet the remainder be a safe hold for the 

 crew. 



CHEMISTRY. 



ROCK-SALT CONVERTED INTO A DUCTILE THREAD. 



M. Gaudin, one of the employes of the Observatory of Paris, has just 

 submitted to the Academy of Sciences a process for converting Mode-salt 

 into ductile thread. You must not shake your head at this, M. Gaudin 

 is no quack. The Academy, at any rate, received his memoir with marked 

 favour. Every body knows that glass, when in a state of fusion, may be 

 drawn out into very slender threads ; and M. Gaudin having succeeded 

 in melting down Rock-salt, discovered that it was susceptible of the same 

 modifications as vitreous substances — that it could be wound round a 

 bobbin, or converted into a solid tissue at will. But of what use, you 

 may say, is this discovery? According to M. Arago, there are various 

 ways of turning it to good account. The torsion balance, which in the 

 hands of Coulomb has proved so useful, is rendered uncertain by the va- 

 riable elasticity of the wires which support the electric or magnetic needle. 

 To remedy this defect, there can be no surer way than to substitute Rock- 

 salt threads for the metallic wire now employed. There are other appli- 

 cations equally interesting. For instance, something is still wanting to 

 give to the oscillations of the pendulum a mathematical certainty. It is 

 hardly necessary to allude to the multitudinous uses of pendulums : yet, 

 when the wire of a pendulum is metallic, we cannot say what modifications 

 it may experience in length during an operation ; but if we substitute M. 

 Gaudin's Rock-salt thread, the results, there is room to hope, will be more 

 conclusive. The importance of M. Gaudin's discovery, so far as the 

 Chemical sciences are concerned, is also great. There is a class of phe- 

 nomena — those that have reference to the internal organization or mole- 

 cular juxtaposition of bodies — with the nature of which we are still im- 

 perfectly acquainted. The modern discoveries respecting light and co- 

 lours show that certain effects result from the properties of molecules 

 themselves, others from their agglomeration : it is more than probable 



that this discovery will throw further light on the subject Correspondent 



in lite Jthenceum. 



GEOLOGY AND MINERALOGY. 



NATURAL EXHALATION OF CARBURETTED HYDROGEN GAS. 



In the vale of Crowdare, near the vilbige of Aberdare, Glamorganshire, 

 there is a waterfall, which has, latterly, become an object of peculiar in- 

 terest, in consequence of a phenomenon, hitherto unnoticed, and probably 

 altogether new in character. It consists of an extraordinary exhalation 

 of gas, spontaneously issuing from the bed of the stream, and which, be- 

 ing ignited, continues to burn, without intermission, with a yellow co- 

 loured flame, interspersed with streams of vivid white, orange, purple, 

 and blue. There are more than twelve apertures through which the gas 

 escapes beneath the water, (causing it to rise and bubble :) others in the 

 dry banks, which increase daily in size. One of the apertures is consi- 

 derably larger than the rest, the flame from which burns about two feet 

 in length, and a foot and a half in width ; at times it bums considerably 

 higher. The soil consists chiefly of argillaceous schist, or fire clay, suffi- 

 ciently hot to burn the hand. Fish caught in the stream have been boiled 

 upon it ; and the friends who accompanied me to the spot prepared a good 

 supper of broiled bacon for ourselves and the spectators. My first im- 

 pression was, that this phenomenon was occasioned by an escape of car- 

 buretted hydrogen from a coal level, but, from its distance from a mine, 

 and the occasional appearances in the flame, I do not think the idea can 

 be correct : most probably it is a mixture of gases. The water has been 

 observed to bubble for many years by the peasantry, but not to any ex- 

 tent, until within the last two months, when the attention of a Stafford- 

 shire miner was attracted by the noise and height of the bubbles, and, 

 subsequently, by the application of a fire. I had an opportunity of wit- 

 nessing this wonderful appearance by night, and regret my inadequacy to 

 describe a sight so interesting. There were not less than twelve large 

 bodies of brilliant flame, of great illuminating power, issuing from the bed 

 of the stream, and underneath the rock which forms the waterfall ; the 

 rich glare of variegated light cast upon the trees and surrounding objects, 

 the noise of the waterfall of the stream, and the reflection of the whole 

 in the water, afforded one of the most imposing sights I ever beheld. I 



collected two quart bottles of the gas, and have given them for analysis 

 to my friend Mr Mougham, of the Gallery of Practical Science, Adelaide 



Street, who will furnish you with a Paper on the results Yours, &c. 



Alexander Byrne. {Correspondent in the Atheneeum.) 



ARBORESCENT OR DENDRITIC FIGURliS IN MINERAL FORMATIONS. 



In many cases the progressive influence of physical causation are more 

 apparent in mineral bodies than in the complicated and living structures 

 of animals and vegetables ; and these examples of resembling figures will, 

 therefore, commence with minerals which present dentritic figures, unin- 

 fluenced by the disturbing actions of vitality. 



The most simple, and one of the most common examples of dendritic 

 figures occurs in the manufacture of the cheapest sorts of ornamented 

 pottery ware, termed the " Mocha_pattern." These picturesque figures 

 are made by children who are entirely ignorant of the art of design. 

 While the vessel is in the unglazed state called Biscuit, it is daubed in 

 given places with a liquid pigment which runs by descent, as the surface 

 of the vessel is inclined, and thus it instantly spreads from trunks into re- 

 gularly subdivided branches ; the rough surface of the biscuit, and the 

 gradual thickening of the liquid pigment, producing these appearances. 

 Streamlets similarly divaricating appear on the sea-shore where little pools 

 of water remain embanked by sand. The water, oozing through the sand, 

 issues in streams, and these subdivide, according to the declivity, into 

 arborescent streamlets, which sometimes again reunite into larger branches, 

 as in the anastomoses between arteries and veins of animal structures. 

 The same appearances often occur upon clayey or muddy declivities, over 

 which streamlets of water flow. Dendritic figures are also common in 

 many stones which were formerly regarded as petrefactions of previously 

 organized structures. In the compact marly limestone called lithographic 

 stone, these figures often occur, and generally on surfaces of laminae, by 

 which it would seem that the ochry pigment had percolated and spread 

 in the same manner as that described respecting pottery. The moss-agate, 

 certain marbles, and mocha-stone, exhibit similar dendritic figures. The 

 entire bodies of certain corallines assume an arborescent character, as in 



the Corillina muscosa of Ellis Sir Anthony Carlisle, in Hie Edin. New 



Phil. Journal. 



PROCEEDINGS OF LEARNED SOCIETIES. 



BRITISH ASSOCIATION FOR ADVANCEMENT OF SCIENCE. — SECT. IX MECHANI- 

 CAL science Paving Streets and Roads with Blocks of Wood. 



Mr J. I. Hawkins made a communication on paving roads and streets 

 with blocks of wood, placed with the grain in a vertical position. The 

 subject, he observed, has latterly become one of considerable interest. 

 Although some patents have been taken out in this country within less 

 than twelve months, there is no specimen of the pavement calculated to 

 afford the means of forming a sound public opinion on the subject. He had 

 attentively watched, from 1827 to 1831, the effect of much travelling over 

 wooden pavement, well executed, in the principal thoroughfare of Vienna, 

 and observed that it appeared to wear away less than any other kind of 

 paving material whatever. In his opinion be was confirmed by inquiries 

 which he made relative to the condition of a piece of wooden pavement 

 laid about three years in the Broadway of New York ; and be had been 

 informed by one gentleman that he saw a stone of nearly 20 tons weight 

 drawn on a carriage over it without appearing to make the least impres- 

 sion. From these circumstances he considered that roads formed of sound 

 wood, with the grain vertical, might be made so even as to constitute a 

 sort of universal railway, on which carriages might be drawn by a small 

 proportion of horse-power, and on which steam-carriages might run as 

 safely and almost as fast as on •railways. The directions to be attended 

 to in the formation of efficient and durable roads on this principle, which 

 the author gave, were comprised under the following heads: — 1. The 

 wood must be chosen from the heart of sound trees. Larch and other 

 resinous firs offer excellent materials at moderate prices. 2. The blocks, 

 which are to be laid contiguously, must be cut to an exact guage, so as to 

 fit closely and evenly together, and no block must be higher than another. 

 3. The depth of the blocks should be at least that of a breadth and a half, 

 a firm lateral support being found necessary to stability. Each block, 

 when rectangular, is supported by four others ; and, when formed into 

 hexagonal prisms, which appears to be preferred, each block is supported 

 by the six surrounding ones. 4. The blocks must belaid on a bed firmly 

 made with gravel, shingle, hard rubbish, or other material, well rammed 

 down, and made even, previously to laying the blocks. 5. A thin layer of 

 onlvan inch of fine gravel must be spread evenly over the levelled surface at 

 the time of laying the blocks, to favour their adjustment. 6. The blocks must 

 be laid so as to present an even upper surface before they are rammed, in 

 order that the ultimate making them level shall not depend so much on 

 the effects of the rammer as on the evenness of the bed. It is essential 



