1-56 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Mat, 



tunately, but competition to urge mamifaclurers and mioers to bring their 

 |)roduce to market of the best quality and at the theapesl possible rule. 



March 30, and April 13. — The discussion on the above paper was con- 

 tinued tiirough both these meetings, to the exclusion of any other subjects. 

 The methods of venlilalion in use in ihe minini; districts were fully de- 

 scribed, and their peculiarities discussed. The causes of accident by ex- 

 plosions, and the consequent choke-diimp, were inquired into; and the fit- 

 ness of the attempted methods of prevention or cure was debated upon. 

 The method of exiiausling tlie air was contrasted with that of forcing it 

 forward inio levels by ii:eans of bellows and pipes. The system used in 

 the north of placing a furnace at the bottoni of tlie upcast shaft was in- 

 sisted upon as that best calculated for the extensive coal-mines of that dis- 

 trict ; while the method introduced by IMr. Gibbons in Stallordshire of ex- 

 hau?tiiig the foul air, by air-heads cut in the lop of the coal, connected 

 with a cliannel in the side of the shaft, terminating in a chimney on the 

 surface, was received as a decided improvement upon the ordinary system 

 in use in that coal-basin, where the extraordinary thickness of 30 feet of 

 the vein of coal renders a peculiar plan indispensable, \arious methods 

 of attempting to carry off the foul air from the ' goof,' whether by additional 

 shafts or by bore-holes, were proposed, aud shown by mining experience 

 to be totilly impracticable, and calculaied lo be rather prejudicial than 

 useful. The interference of Government was strongly insisted upon, and 

 as decidedly objected to by those miners whose long experience and good 

 judgment entitled their opinions t(v deference and consideration. It was 

 shown that the foreign mines which were under the constant superintend- 

 ence of Government engineers, far from being exempt from accident, were 

 not only more liable to the effects of deficient ventilation, but that the actual 

 loss of human life was greater than in England; and that if our mines 

 were subject to the same annoying trammels, tjie price of fuel must be un- 

 duly raised, without any corresponding advantage, or any immunity from 

 danger. There could be no objection on the part of the coal-owners to the 

 formation of an association for regularly inspecting and reporting upon the 

 states of the various mines, and the communication between the various 

 districts of the methods found to succeed best under the attendant peculiar 

 circumstances; but reasons were given why such a power should not be 

 placed in the hands of Government officers. 



The subject of safety-lamps and their uses was also discussed : Dr. Reid 

 Clanny's first invention of the lamp in I8I3, which necessarily failed from 

 its cumbrous form and general inapplicability for working purposes, and 

 the recent form he had adopted, combining portions of the other lamps in 

 use, so as to show a brif;ht light and yet be free from danger: the extra- 

 ordinary coincidence of inventive thought between Sir Humphrey Davy 

 and Mr. George Stephenson, the one acting upon purely chemical theory, 

 and the oiher upon mechanical knowledge and practice, and yet both simul- 

 taneously producing lamps which were almost identical, and which still 

 remained very generally in use under the names of the "Davy" and the 

 " Geordie." 



April-20.—" Onthe De/ecls in the Principle and Constiuction of Fire - 

 pronf liuHdiiigs." By Mr. Kairbaii.n, of Alauchester. The paper com- 

 menced by insisting strongly on the danger ol making use of cast iron 

 beams of large span, without intermediate supports, unless the dimensions 

 of the beams were very large, and pointing out the treacherous nature of a 

 cbrystalline metallic body, such as cast iron, when applied to support 

 heavy weights in the construction of buddings. After some further re- 

 marks on the importance of a tliorough knowledge of the laws which go- 

 vern the use and application of cast iron as a material in building, under 

 the various strains lo which it n ay be subjected, ti.e author proceeded to 

 investigate the circumstances connected with the fall of Messrs. Gray's 

 cotton mill at Manchester. This building was stated to be about 40 feet 

 long, and 31 ft. 8 in. wide, and to consist of two storeys in height, contain- 

 ing the boilers below and the machinery above, over which, instead of a 

 roof, was a water cistern, covering the whole extent of the building. The 

 first floor was composed of large iron beams, of 31 ft. 8 in. span, without 

 intermediate supp<irl ; on these beams brick arches were turned, sustaining 

 the whole weight of the upper part of the building. The author then de- 

 monstrated, that these large beams were totally inadequate to support the 

 weight of the superincumbent mass, especially as the whole pressure was 

 upon the centre of the beams, whicii were of a form ill calculated to bear 

 Ihe pressure ; added to which, the wrought iron trussing was so badly ap- 

 plied, ihai the breaking strain was arrived at before the truss roils were 

 brought into a state of tension. The consequence of this was, that one of 

 the lower beams broke in Ihe centre under a less weight than it had pre- 

 viously supported, both under pieliminary trial, and when the cistern was 

 fuller than at the time of the accident. The paper closed with some re- 

 marks on the delicale and invidious duty of reporting on such acciilcnts 

 as those in which the reputation of genllemen of high professional acquire- 

 ments maybe involved; and the author expressed bis reluctance in eou- 

 denining tne construction of the building in question. 



In the discussion which ensued, it was argued that, if proper proportions 

 of material had been observed, the accident oughtnot lo have occurred. It 

 appeared evident that the wrought iron truss rods had been so put on, lliat 

 they allowed more than the breaking strain of the cast iron to be arrived 

 at, before they came into operation. Tlie instances of the irusstd-beam 

 bridges, extensively used by i\Ir. Stephenson, and oilier engineers, on rail- 

 ways, were quoted to show, that by a judicious employment of wrought 

 iron trusses upon cast iron beams, large spans might be crossed with safety ; 

 and even, in some cases, where, liom unseen defects in the metal, a beam 



had fractured, the brass rods had sufficed to support the structure, and 

 enabled the traffic to be continued across the bridge until the repairs could 

 be effected. In all cases a strength of not less than four to one should be 

 employed, and for such uses as the iron beams of pumping engines, which 

 were exposed to great vibration, and sudden shocks, from the sudden influx 

 of steam below the piston, or ihe accidental breaking of a pump-rod, the 

 proportions of seven or eight lo one should be observed. 



CHEMICAL SOCIETY. 

 March 15.— Lieut.-Col. P. Yorke in the Chair. 

 " On the Decomposition of Water by Platinum and Black Oxide of 

 Iron." By Dr. G. WiLsis. — The interesting researches of Mr. Grove, oa 

 the decomposition of water by white-hot platinum, lately made public, 

 have necessarily led to many conjectures concerning the cause of a pheno- 

 menon so extraordinary and unexpected. Cerlain remarkable peculiarities 

 possessed by plalinum, aud in a less degree by others of the noble metals, 

 have thrown some doubt on the powers of mere heat to effect the decom- 

 position of a compound of such stability as water. The repetition of the 

 experiments with other substances not open lo the same objections is, how- 

 ever, a matter of great difficulty. \thile reflecting on the means of ac- 

 complishing this, the attention of the author was accidentally called to the 

 evolution of small bubbles of gas from the fused globules of oxide of iron, 

 produced by burning iron wire in oxygen gas, falling into water. In the 

 hope that ihis might allord some clue to Ihe phen -menon in question, ar- 

 rangements were made for performing the experiment in such a manner that 

 the gas evolved should be collected and preserved for examination. This 

 was easily done by directing the fused globules of oxide, by means of an in- 

 clined plane of tin-plate, from the jar in which the w ire was burned, under 

 the edge of an inverled funnel entering a test-tube immersed in the water 

 of the pneumatic trough. The quantities of gas disengaged by the globules 

 were very unequal ; some gave none at all. Generally, globules from Ihe 

 thickest wire produced most gas. The gas on examination, however, was 

 discovered to be pure hydrogen, merely sullied Ijy a trace of atmospheric 

 air ; and its origin » as at once explained by an eXamiualion of the globules 

 themselves, for very many of these latter were found lo contain in their 

 center a kernel of fused metallic iron, which had escaped oxidation when 

 the wire was burned in the gas, and which in a highly heated state coming 

 in contact with water occasioned ihe decomposition v( a portion of the lat- 

 ter lu the usual manner. The black oxide of iron does not appear to have 

 the poller of further abstracting the oxygen from water. This experiment 

 is, therefore, valueless in elucidating the fact of the decomposition of water 

 by healed platinum. It is probable, loo, that the temperature of the melted 

 globules of oxide of iron is really niucli inferior to that of plalinum in the 

 stale in which it is employed in Grove's experiment, namely, just at the 

 point of fusion. 



Dr. Wilson then argues, that the decomposition of water by a white heat 

 may be referable to the mechanical disruption of the particles in direct 

 contact with the heating body, and not lo Ihe decomposing power of heat 

 alone ; as the statement that water can be produced by Ihe same processes 

 that disunite its elements would be tantamount to affirming ihal unlike 

 ellects may flow from Ihe same cause, wiihout any alteration in the quali- 

 ties or coudilioDS of the water. 



REVIEWS. 



Encydopcsdia of Civil Engiiuering, — Historical, Theoretical, and 

 Practical. By Edward Cresy. Royal fevo. London: Longman 

 and Co. 1847. 



[second notice.] 



We paused last month in our notice of Mr. Cresy's book, at the in- 

 teresting subject ol engineering in England, of which we only gave one 

 extract, tluit relating to New London Bridge. 



Docks deseivedly occupy a considerable space in Mr. Cresy's book, 

 for tliey are works in wliicli the English have peculiarly distinguished 

 themselves. Indeed, the tidal phenomena of the English coasts have 

 had as much to do with the extension of this class of work as any 

 commercial demand, for whereas in the coasts of Holland and the 

 United Slates, anil in many parts of the world, the rise of tide is littls 

 or nothing, on the English coasts it is in all places considerable, and 

 particularly favourable for all kinds of docking operations. In France 

 docks and basins ;ire chiefly for naval purposes, and in the Mediter- 

 ranean tin re are no tides, so that Eiigl.uid stands almost alone in a 

 class of works which demand great scientific resources, and which 

 are frequently on a scale of colossal grandeur. 



Mr. Cresy in takirg up this subject prefaces it by a description of 

 the iialural features of each river aud harbour, which is essential to a 

 proper appreciation of the engineering works. In the Thames, Mr. 

 Cresy states that there are not only the commercial docks in Ihs Lon- 



