222 



THK CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Jui.v, 



PROCEEDINGS OF SCi;2?'?TIPIC SOCIETIES. 



INSTITUTION OF CIVIL ENGINEERS. 



June 5. — Joshua Field, Esq., Prosidetit, in the Chair. 



The paper read was a "D''scrt/ttion of a Method of RoUhuj Hitrs for Sun- 

 />emion BriiUjea, and oilier like purjjoses." 15y Mr. Thomas Howabd, 

 A. Inst. C.E. 



It was desciil)e(l th.it hy the ordinary process of mannfacture, tlie head, 

 or end of the hnk, cut of whicli the eye, or liole for the eonnecting pin, was 

 hored, liad heen snirietinies weldeil on to a parallel rolled har, or, at other 

 times, heen hammered to the ri quired form ; hoth these methods were, liow. 

 ever, ohjectionahic, owing, in the former case, to the insecurity, and in the 

 latter to tlie tediousness and exjiense. By the method introduced hy Mr. 

 Howard, the hars were rolled at once into the requisite form ; the shingle, 

 or faggot, was first passeil longitudinally, at a welding heat, through grooved 

 rollers, in the ordinary manner, and then, hefore lieing drawn down to the 

 intended thickness, was carried to rollers having hosses, or increased diame- 

 ters at the places corresponding to the heads to be produced, and thi-re 

 passed to and fro hetween the rollers transversely, or across the breadth of 

 the bar, thus receiving a pressure only at the enlarged parts of the rollers, 

 which gave the nei-essary increase of breadth at the heads ; it was then 

 taken to plain finishing rollers, and drawn out longitudinally in the usual 

 manner, until it attained the required length and thickness ; the heads being 

 alternards trimmed by machinery to the exact dimensions, and the holes 

 drilled for the pins. 



It was stated that the chains of the large suspension bridge, erected by 

 Mr. W. Tierney Clarke over the Danube, at Pesth, which lately so satisfac- 

 torily withstood the heavy strain bronuht upon it hy a retreating army, were 

 constructed 'on this system at the King and Queen Ironworks at Kother. 

 hithe : as were those for lifting the tubular bridge at Conway, and over the 

 Menai Straits: and also that the links for a bridge now erecting by Mr. 

 Vignoles, at Kietf, in Russia, were manufactured by another firm, under 

 license to use Mr. Howard's system. 



Some interesting observations were recorded of the results of the experi- 

 jnents for determing the strength of these hars, showing thera to possess 

 great elasticity and freedom from permanent set. 



The discussion elicited some useful remaiks as to proportions of the area 

 of the body and of the head, and of the diameter of the pin, which, it was 

 shown, had much influence on the resisting power of the heads ; — the larger 

 the pin the less being the tendency to rupture the eye. 



The process appeared to he admitted as a great improvement on the ordi- 

 nary mode of manufacture, and tending to give confidence to the engineer 

 that his designs could be executed in metal, uninjured by manipulation. 



June 12. — The first paper read was " A Description of the Construction 

 of a Cottar Roof, with arched trusses of bent ti/nber, af East Iforsetei/ 

 Parli." By the Right Honourable the Earl of Lovelace, A. Inst. C.E. 



The roof which covered a hall of fifty-six feet long hy twenty-four feet wide, 

 was described as being sustained by four arched trusses, springing from stone 

 corbels. The ribs of these were each composed of four layers of deals, 

 three inches thick, bent to the required form by steam heat. All the mould- 

 ings surrounding the tracery were also bent to the required forms in the 

 same manner, thus giving great strength and lightness, as well as performing 

 the work with greater economy of labour. The tracery was cut out from 

 two thicknesses, half-an-incb each, of tub-stave oak, glued together, with the 

 fibres at right angles to each other, which facilitated the carving, and gave 

 greater strength to the minute tracery. 



Tlie ceiling was formed of half inch diagonal boarding, and as the slate 

 battens crossed it in a horizontal direction, the roof was strongly braced 

 against the action of wind, and the staining of the alternate boards gave a 

 p'leasing variety of effect. 



1 his kind of construction was first suggested by Colonel Emy, in his work 

 on Carpentry, hut he had applied it to much llatler roofs of large span, 

 whereas Lord Lovelace's intention was to demonstrate its ajiplicability to 

 roofs for edifices in the Pointed and Tudor styles, and to show that gieat 

 advantage would result from bending timbers rather than cutting them to 

 tlie requisite forms; that the thrust of the roof might he entirely tuken 

 from the upper part of the walls, and carried far down them, and that such 

 a construction might be adopted as would satisfy every condition of solidity, 

 and, at the same time, admit of considerable decoration. 



In the discussion which ensued, the ingenuity of the design and of the 

 mode of execution of the roof were equally approved, and the noble Earl 

 was deservedly complimented for the motives nliich induced him to bring to 

 the Institution the account of one of his works. 



The second paper was "A Stalemrnf of Observations made on the Initial 

 and Terminal Velocities of Trains ni descending Inclined Planes." By Capt. 

 \V. MooRsoM, M. Inst. C.E. 



Till oliservalions were eighty-two in number, and were made during the 

 ordinary passing of trains on the Waterford and Kilkenny Railway, the 

 gauge of which is !j ft. 3 in., over two adjoining inclines, each falling at the 

 rale of 1 in 100 for upwards of a mile and a half, with a short interinediaie 

 level between them. 



The speeds at which the descent was begun, varied from 20 to nearly 44 

 miles pc r hour, and the loads varied from 32 to 94 tons. 



One of the planes presented for the greater part of its length two curved 

 of a radius of IjJ- and 1^ miles respectively, and the other plane was strai^jht 

 for part of its length, but contained a curve of 2J miles radius. 



The general results in the more curved plane were, that initial velocities 

 of 20 to 30 miles per hour, at the top of the plane, became terminal at ve- 

 locities of 24 to 28 miles per hour; and on the siraighter plane the same 

 initial velocities became terminal between 20 and 31 miles per hour. 



Again, on the more curved plane, initial velocities between 30 and 40 

 miles per hour, became terminal at velocities between 29 J and 31 J luiles 

 per hour; and on the straighter plane the same initial velocities became ter- 

 minal at 30| to 33 J miles per hour. 



Initial velocities above 40 miles per hour were noted only upon the more 

 curved plane, and became terminal at 30 to 31 miles per hour. There did 

 not appear to he any constant proportion between tlie load in motion and 

 the terminal velocity ; but the latter appeared to be dependant more upon 

 initial velocity than upon the weight or character of frontage of the trains. 



The general practical conclusion vvas deduced, that the question of gauge 

 had little or nothing to do with terminal velocity derived from gravity, and 

 that the views generally entertained by engineers, during past years, of the 

 great resistances experienced by trains at high velocities were borne out by 

 the observations recorded in the paper. 



The proceedings of the evening concluded with a paper by Lieut. -Colonel 

 Hariy D. Jones, R.E., M. Inst. C.E., descriptive of the Bridge at \thloue, 

 erected under the authority of the Shannon Commissioners, from the designs 

 of Mr. Rhodes, M. Inst., C.E. 



The paper described the great difficulties experienced from the rush of 

 water into the cotferdams, through the porous gravel stratum in which 

 they were placed, and the ingenious modes of overcoming these impedi- 

 ments. The biidge, of three arches of stone and one of iron, the latter 

 having the means of opening for the navigation, was fully described, and 

 was admitted to be not only a beautiful structure, but to have been built for 

 a so. all sum (about 24,000/.) considering its extent. A beautiful set of 

 drawings, and the printed specifications for the work, illustrated the paper. 



June 10. — The paper read was " On the Employimnt of High- Pressure 

 Steam, working expansively, in Marine Eayincs" By Mr. John Seaw.\rd, 

 M. Inst. C.E. 



This communication was described to be the substance of a reply, by the 

 author, to some questions addressed to several eminent engineering firms, by 

 the Hon. H. L. Corry, M. P., when secretary to the Admiralty. This reply was 

 found to furnish so much useful information, and so completely to open the 

 question of the advantage or disadvantage of using high-pressure steam, 

 and of cutting off the steam at various portions of the stroke, that it was 

 conceived it would be advantageously produced at the Institution, in order 

 that the subject should be fully discussed. Unfortunately, the absence o( 

 the principal members at the floating of the first tube of the Britannia- 

 bridge frustrated the latter expectation, but the substance of the paper 

 appeared to be fully appreciated. 



The argument was so continuous that it would be difficult to attempt to 

 do more than to give a taint idea of it, as the limits of this account would 

 not suflice for an alistract of it. It first reviewed the mode of working ma- 

 rine engines for some years past, and noticed the gradual change that had 

 occurred, particularly the tendency to use high-pressure steam, instead of 

 that of a pressure of about 41b. above the atmosphere. It then examined 

 the system of cutting off the steam at various parts of the stroke; and as, 

 at the same time, a remarkable augmentation had occurred in the speed of 

 the vessels, which was naturally attributed to that cause, it inquired mi- 

 nutely into these several causes and etTecls, as well as the considerable 

 reduction in the consumption of fuel which took place, enabling the vessels, 

 consequently, to make longer voyages, or to carry less fuel forgiven distances. 



In this examination, all the arguments for and against the use of high- 

 pressure steam, and the presumed gain or loss of mechanical power in the 

 use of the expansion piinciple in the cylinder, were canvassed at length ; 

 and the paper wound up with replies of the author to the three questions 

 from the Admiralty, to this effect : — " The highest pressure of steam that 

 we have, in any case, put upon a marine boiler of our own construction, was 

 about 16 pounds to the sqmre inch; hut we are not inclined to repeat the 

 experiment, as we feel assured that we can obtain equally good results with 

 steam of a lower pressure — fiom 10 to 12 ib. is the usual pressure we em- 

 ploy in the merchant service for engines and boilers of coinpaiaiive small 

 power. The steam pressure at present em|iloyed in the service is about 8 Ib. 

 per square inch. W'e consider steam of this pressure to be well adapted for 

 the exigencies of the service ; we believe it is calculated to secure all the 

 important advantages of iiower, economy of weight and space, in a very 

 eminent degree ; those advantages will, in some respects, be slightly in- 

 creased by augmenting the steam pressure to 10 or 12 lbs. to the square 

 inch. We strongly recommend that the steam eniployed in the navy should 

 not be of greater pressure than 10 lb. per square inch, or in extreme cases 

 12 Ib. to tlie square inch ; any material increase to the latter pressure will 

 be attended with considerable risk, without any adequate advantage." 



In the discussion which ensued, these propositions were, to a certain ex- 

 tent, concurred with, hut with limitations as to the introduction of other 

 fiirms of boilers ; and it was explained that the arguments of the paper 

 were only applicable to condensing engines working expansively, and, there- 

 fore, Icit the question of the introduction of the using of high pressure 



