470 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[December, 



tity of persiiirable iiiiittcr is not carried off fi'oin the lungs and skin, t!ie in- 

 jurious cft'ccts of wliicli have been dearly cstaljlislicd liy .M. Qiietelet in his 

 woric on man. Tlic injurious otfects of an excess of nitrogen and carbonic 

 acid gas are too well known to require coninient. 



Tlie author next treats of liie best nietliods of wanning buihlings in order 

 to secure a liealtliy state of the atinos[:hcre ; and having shewn the disad- 

 vantages of applying heat directly to any surface, he points out tlie method 

 of applying it indirectly, as hy steam or hot water, eontainei! in iron pipes : 

 the latter is more economical and simple, affords gi-eater pcrnKincneo and 

 equality, admits of a lower uniform temperatm-e, and any form of heating 

 surface. The temperature of the mctallie surface rarely exceeds 180° F. and 

 never reaches 1^12 F., which is too low to decomjiosc in any aj)preeiable de- 

 gree the organic matter contained in the air. The only effect is to increase 

 the capacity of the air for moisture, which is readily obvi.".ted. The surface 

 whicli is intended to distribute the beat should be a good conductor and 

 radiator, and the material which )ircsents this combination in it< highest de- 

 gree is iron ; the .iniount of heating surface which will be required depends 

 on the Innhiing to be warmed, and on a great variety of eircumstanecs ; Init 

 as an apjn'oximatc rule it may be laid down, that for a chinch or similar 

 public Iniilding the cubic contents of the hiiihling divided by 200 will give the 

 number of feet of surface requisite for a teunierature of from 55" F. to 58° F. 

 in the coldest wcatiier ordinarily experienced in this country. The form of 

 the heating surface is immaterial as regards (he action of the apparatus, luit 

 the time requisite to obtain a given temperature, and the permanence of that 

 temperature, depend on tlie mass of be. ted m.atter ; the relative times of 

 heating and cooling being inversely as the mass divided by the sui)erfieies. A 

 rapid cirenlation of the water may be oljtaincd by increasing the elevation of 

 the pi]ies aliovetlie I)oiler, liut it is considerably inducnced by any alterations 

 in tlie bore of the pi]:es. One great advantage in this apparatus is its perfect 

 safety, as tlie water at some point is always open to the atmosphere, whereas 

 in the system of hermetically sealed pipes, containing steam or hot water 

 under a pressure of from ten to fifty atmospheres, tliis seciu-i!y can never 

 exist. 



3.' — The author lastly treats of ventilation ; a subject of the greatest im- 

 portance, independent of the changes already alluded to as produced in the 

 atmosphere by overheated surfaces, since all air respired from tlie lungs is 

 found to b.ave lost a ])roportion of its oxygen, and to have acquired a pro- 

 portion of carbonic acid gas and vapour, and the quantity of air which ^vill 

 require to he changed maybe taken as 3.\ cnbie feet per minute for each jier- 

 son a room contains. The author dwells at considerable length on the phy- 

 siological eft'ecls consequent on these changes, anil details several striking 

 instances of the great advantages resulting from iminoved ventilation, in 

 places wdiich had previously lieen unhealthy. All ventilation may he placed 

 in one of two classes, the natural or the meeb.anical ; in the former, the ex- 

 cess of temperature of the air is the primum mrihile of the efflux, and the 

 rapidity of the discharge may be nuieh increased by artilicially raising the 

 temperature of the discharging pipe. Verjtilatiou hy mechanicaT means, as 

 by pumps, orhy fans rotating witli a great velocity, may be most advantage- 

 ously enqiloyed, wherever mechanical power is used for other ]iiirposes ; the 

 great ellieacy of this latter nioile is proved most unquestionalily by the ex- 

 perience of the manu.facturing districts. The former metliod has recently 

 been tried on a very large scale at the House of Commons, anil it is calculated 

 by Dr. Ure that 38 times more fuel is expended in jiroducing the same effect 

 by chimney ch-aughts than by mechanical power. It a]qiears, however, that 

 the natural method of ventilation, by the spontaneous effusion of the heated 

 air, through openings in the ceiling, is the best calculated for ordinary pur- 

 poses ; hut thiit in all extraordinary cases ventilation hy some mechanical 

 means is the only economical and efficacious method. 



A ]>ai)er was read on 



' Exjxrhnenial Researches upon the cost qf the Light affonled l)y dijfermt 

 Lamps and Candles' By Anubew Ure, M.D., F.K.S., &c. ixe. We pub- 

 lished this paper in the last September Journal. 



June IS. — The President in the Chair. 



A pajier was read giving ' An Account nf the New Stone Brtdgrs over the 

 River Lea, at Stratfurd-le-Bow,'' By John Buldry Hedman, Grad. Inst. 

 C. E. We published engravings and an account of this bridge in the last 

 April Journal. 



* A neir plan of comfructton of Slldinrj Gates for the Entrance Lodes of 

 Bocks, iS^'c.' By J. C. Singels, Engineer of the Waterstaat, llollande, &c. 



The imiirovement suggested consists in substituting for the ordinary Lock 

 Gates, Sliding Gates, traversing the ends of the lock on rails laid on sills, 

 drawn across by chains and cajistans. The author in proposing this mode of 

 constmetion assumes, that wlien a lock exceeds 50 feet in width, ordinary 

 gates must be abandoned and caissons used. The advantages offered by it 

 are, diminishing the length of the lock by that of the ordinary opening gate, 

 consequently the volume of water to fill the lock is lessened in the same de- 

 gree, and reducing tlie number of tlie locks; for as a small elevation is essen- 

 tial to the strength of the ordinary gates, the sliding gates may on the con- 

 trary be made of almost any lieiglit without any fear of impaii'ing their 

 strength or solidity. 



In the description of the I'hms aeeompanying the paper, great stress is laid 

 on the whole length of the lock, with the cxce|)tion of that part across which 

 the gate traverses, bciug-construi ted on an invert arch, liius giving gi'eater 

 solidity than where a lint floor only is used, cither for the v\hole length, or 



for tlie wide space necessary for the ordinary gates to swing upon. It is 

 aeknowdedged that more masonry is required in this mode of construction, 

 but it is argued that the extra expense will be met by the saving in the 

 length of the lock and in the quantity of the water used. 



In constructing the Sliding Gate, the timbers of which are cross braced 

 and strutted, and tlicn covered with planking on both sides, the rule to he 

 observed is, that the thickness of the gate is one-fourth of the width of the 

 lock, £0 that the main bracing timbers are at an angle of 20°. These are 

 crossed by other timbers, also diagonally braced, extending the vertical height 

 of the gate, so as to give tliat eombination best calculated to withstand the 

 pressure of the water on either side. To obviate the difficulty of setting in 

 motion so heavy a mass as the sliding gate, it is proposed to place within it 

 some barrels tilled with air, which hy their buoyancy would relieve the 

 rollers of some portion of the weight, and enable the gate to traverse more 

 easily. 



Mr. Palmer observed, that the author could hardly be acquainted with the 

 modern practice in constructing locks in this country, as timber had for a 

 long period been but little used in the lock chauiber. His practice had been 

 invariably to have an invert arch at a lower level than the lock chamber. 

 He was now constructing at Port Talbot, in South Wales, a lock of 45 feet 

 span, in which there was at invert arch built of stone, 3 feet thick, with lias 

 lime, ]ilaced on a stratum of concrete, 2 feet thick, the concrete being com- 

 posed of four parts of gravel and sand to one of lime ; above this invert, the 

 floor was tilled in with 2 feet thick of brickwork, laid in Roman cement. 

 Beneath the roller curbs, stones were placed to bed them upon. Each lock 

 gate weighed about 40 tons, one half of which was borne by the heel-post 

 and the other half on the rollers, yet there was no difficulty in moving it at 

 pleasure. The depth of the water was 30 feet, and sometimes the whole 

 column pressed on the gates, yet no injury was feared. There had been great 

 difficnlty with the water during the course of construction, but the invert and 

 the side walls placed on it were perfectly sound, and able to withstand any 

 pressure. Me apprehended that the sliding gate would be much heavier than 

 the common gate — that the expense of construction would be greater — and 

 he could not discern any compensating benefit to result from its adoption. 



June 25. — John Macneill, Esq. in the Chair. 



The following were ballotted for and elected : J. F. Hanson, John Llewellin, 

 and W. Llewellin, as Associates. 



The following coinmuuieations were read in part :— 



' On Steam Engines, particnlarhj trith reference to their eonsumption of 

 Steam.' By Josjau Parkes, M. Inst. C. E. 



' On the Analysis of a portion of the Iron Heel-plate of the Stern-post of 

 the John Bull, Steatn Vessel.' By David Mus:iet, A. Inst. C. E. 



The action of the sea water had converted the iron into a substance some- 

 what resembling plumbago. Mr. Musbet, after analysiug it, considers this 

 substance, which had been called marine plumbago, to be composed nearly as 

 follows ; 



Carbonic acid and moisture - - - 20 

 Protoxyde of iron . - - - 35"7 



Silt or earthy matter . - - . 3'2 

 Carbon - - - - - - 4I'l 



100 



' On amethod of Dowelling Timber hi/ Iron Dowels and Asphalte. By M. 

 J. Brunel, M. Inst. C. E. 



' On ttte Ejponsion of Iron and Stone in structures, as shewn hy olserva- 

 tions on the Southwark and Staines Bridges' By George Rennie, F.R.S. 

 &c. &c. 



* A theoretical calculation of the amount of Fuel saved hy working Steam 

 expansively.' By J. W. Luiidock, lion. M. Inst. C. E. 



' Tlie following communications were announced as received :— 



* Ohservalions on the ej^iciency or gross power of Steam everted on the 

 piston, in relation to the reported duty of Steam Engines in Cornwall at dif- 

 ferent periods.' By John Scott Enys, A. Inst. C. E. 



'Specifications and Drawings^ of the Gas Works at Middleslro-on-Tees.' 

 By Petkr HENnEas;oN, A. Inst. G. E. 



' On tlie cons'ru -tion of the Clierbourg Breahvater ; with a Drawing* By 

 G. S. Ualrymple. 



' Drawing and Description of the Coffre Dam at the new Houses of Parlia- 

 ment.' By G. S. Dalrymi'le. 



The meeting of this evening concluded the session of 1839. 



INSTITUTE OF THE ARCHITECTS OF IRELAND. 



On Monday evening, 11th ult., the members of the Royal Irish Academy, 

 Sir William ilamiltnn in tlie chair, called upon Mr. Morrison, Vice-President 

 of the above-named learned body, for a slateinent of the nature of its objects ; 

 and the learned gentleman having comjilied with the demand, a resolul ion 

 in favour of the Institute \\i\» moved, sseonded, aud unRuimously adopted. 



