388 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[November, 



hard stone called " klinkers " is also niucli used for ashlar work, and an in- 

 ferior quality of stone for rubble-work, with bricks. 



The mortar used up to a short distance above the standard tide level, vfas 

 ni;:de from stone lime, and above that, of lime made from sea-shells ; cement 

 was alao used in several parts. 



The modes of constructing these various works are given in minute detail ; 

 many of them, ditt'ering materially from the English method of construction, 

 possess great interest ; particularly those v/hich relate to the embankments 

 and the fascine work. 



A description is then given of the Canal of Oegstgeest, which is a pro- 

 longation of the Canal of Katwyk for the purpose of bringing into the 

 latter, the waters from the Lake of Haarlem ; as well as a means of carrying 

 off the waters of a portion of Rhynland, during and after the drainage of 

 the lake. 



In consequence of the establishment of this canal, the Canal of Katwyk 

 required to be enlarged, which was done to the extent of rendering it 52 

 metres (50'S6 yards) wide, with an average depth of 2'20 metres (2'40 

 yards) below the standard level. The bridges were also enlarged, and it is 

 now contemiilated to add two openings to the inner lock, those of the sea 

 locks being already of sullicient capacity. 



Having described the works in detail, the author enters into some general 

 remarks upon the effuct produced by the canal, one of the principal being its 

 beneficial use in determining the possibility of draining the Lake of Haarlem. 

 Thirty-five years of experience, have demonstrated that this canal is the 

 surest remedy for the peculiar position of the district of Rhynland with 

 regard to drainage ; the constant action of the North Sea has made no im- 

 pression upon the simple but solid masonry of the sea locks, in fact, the 

 Canal of Katwyk appears to be one of the most remarkable hydraulic works 

 ever constructed for the protection of Holland. 



The author concludes the paper by stating, that although he could with 

 difficulty spare the time from his professional labours on the Amsterdam 

 railway, of which he is the engineer, he was induced to undertake the labour 

 of drawing up this memoir, by the subject being one of those proposed by 

 the Institution of Civil Engineers, in the list for Telford and Walker Pre- 

 miums for 1842, and by the desire of doing justice to the memory of his 

 father, whose early decease alone prevented his name from becoming as ex- 

 tensively known ps his talents deserved. 



The paper is illustrated by nine comprehensive drawings and charts, with 

 some lithographic views, a portrait of Mr. Conrad, sen., and the medal which 

 was struck on the occasion of the first opening of the sluices. 



" On the Construction of the Bridges on the Bolton and Preston Railway." 

 By A. J. Adie. 



This paper, which was written at the request of General Pasley, and by 

 him communicated to the Institution, contains a description of the bridges 

 over the Cowlin firook, the Lancaster Canal, and the Chorley Road, which 

 alone possess any peculiarities of construction, and they formed the types 

 upon which the other bridges were built. 



In Colonel Sir F. Smith's report upon the Cowlin Brook bridge, he advised 

 great attention being paid to the bridge on account of its " unusual slight- 

 uess, and the badness of tb.e ground upon which it was founded." The 

 author states, that the latter circumstance induced him to design the present 

 proportions of the work as he' wished to reduce the weight of the piers as 

 much as jossible; he therefore ventured to deviate from the original design 

 given by Mr. Rastrick. The result has justified his anticipations, as " after 

 the mo^ careful inspection not a single crack nor a splnitered stone can be 

 detected." 



The ground where this bridge was to be placed, was found to be a rotten 

 and compressible mixture of moss, decayed wood, and sand, ^\ith a few large 

 stones; a foundation was made for each pier by driving in piles 20 feet long 

 by 12 irches square; upon these were placed the footing courses of Lim- 

 erick stone 8 inches thick ; the piers were built hollow, so that the utmost 

 weight placed upon each superficial foot should not exceed 5-2- tons, which 

 the author states to be a light load for ashlar work : — " In Edinburgh there 

 are old rubble walls 34 in. thick and above 100 f(. high, which in addition 

 to all their proportion of eight floors, and a roof, have 6J tons on each su- 

 perficial foot of the bottom courses, and there is a brick chimney in Bolton, 

 the bottom courses of which support 8. J tons on the superficial foot." 



The bridge consists of eight arches, each of 30 ft. span ; the arch stoues 

 are 18 in. thick, of hard sandstone from the Whittle hills, except seven 

 courses at the crown, which are from a better quarry at .\ckrington, near 

 Blackburn. 



The author then mentions, as a precedent for such dimensions, some arches 

 constructed under Mr. Jardine's direction on the Edinburgh and Dalkeith 

 Railway ; they were of Craigleith stone, semi-elliptical in form, of 24 ft. 

 span, with a rise of 4 ft., or ^th of the span; the stones for these arches 

 were 12 in. deep at the springing, and 9 in. deep at the crown; the abut- 

 ments of one of them are founded on platforms of timber, without piles, 

 resting upon soft plastic blue clay ; they have been standing for upwards of 

 ten years, and exhibit no signs of failure. Another arch is also mentioned, 

 constructed by the same engineer, over the South Esk, near Dalkeith, the 

 span of which is 55 ft., and the versed sine 12 ft.; the keystone is 18 in. 

 deep, and the springers 21 in. in depth. 



The author objects to placing a mass of earth upon the haunches of the 

 arch, as, from the tremour caused by the passing of the railway trains, the 

 eaith has always a tendency to be wedged in between the side walls and to 

 force them out ; he therefore left voids above the arch stones, allowing only 

 sufficient weight of masonry upon the haunches, and thus securing the rapid 

 hardening of the mortar ; for this latter reason also the walls of rnbblc-work 

 never much exceed 3 feet in thickness, and they have been found much 

 stronger in consequence. 



The railway is carried over this viaduct on longitudinal bearers, 13 inches 

 deep by 6 inches thick, laid on planks 3 inches thick ; the bearers and 

 planks are not fixed together with a view to diminish the vibration of the 

 passing trains : this method of laying is stated to be very effective in tills 

 respect. 



The Lancaster Canal Bridge was originally intended to have been a direct 

 span of 00 feet, constructed of iron, but the directors subsequently decided 

 on building a skewed stone arch of 25 feet span on the riglit angle. The 

 arch is semi-elliptical on the square, with a transverse axis of 41 feet 2 inches 

 and a semi-conjugate axis of 8 feet 9 inches ; the arch stones are 2 feet 

 3 inches on the square at the springing, and 1 foot 6 inches at the key-stone ; 

 the bed joints intersect at right angles all the lines of sections of the intrados, 

 made by vertical planes, parallel to the elevation; and it is that property 

 that causes the chamfer lines of the beds of the stones to diverge from the 

 springing to the crown. These lines of the curved joints are easily laid down 

 on the sheeting of the centres from a full-sized development, and by lines 

 drawn at different heights, parallel to the springing of the arch. The lines 

 of the radiating bed joints are always perpendicular to the tangent of aa 

 ellipse of the same form as the elevation of the bridge, the moulds used to 

 form this being applied in the plane of the elevation. The twist on the 

 length of the beds of the courses was taken from full-sized skeleton moulds 

 of the form of the oblique elli|)se or elevation. The five courses running 

 parallel to the abutments are all of the same form and have the same amount 

 of tv(ist on the beds of each stone, except the end stones of the courses, 

 which are varied in length to suit the general breaking of the joints of the 

 courses resting together. The centre pait of the arch is plain square 

 work. 



This mechanical method of finding the lines, and the twist of the radiating 

 beds for an elliptical skewed arch, is destitute of the scientific accuracy of 

 the mode by which Mr. Buck calculates his spiral lines for oblique bridges, 

 of which the section at right angles to the abutment is an arc of a circle ; 

 but the workmen had no difficulty in putting it in practice, and the author 

 states that he would have had more trouble in constructing trussed centres 

 for a flatter curve of a circular arc, and at the same time keeping the towing 

 path of the canal open. He states that he has not met with any description 

 of an arch executed in this manner, but he considers it the only true prin- 

 ciple. Every very thin section par.iUel to the elevation is a proper elliptical 

 arch, and there is a very great saving of stone from the smallness of the 

 twist on the curved beds as compared to the common method of working 

 them. 



The Chorley Road Bridge is a compound of the common and skewed 

 arches, which the author finds convenient and economical. He has executed 

 several upon this plan ; they are as perfect as the best common arches, and 

 free from skirting of the soffits of the stones. The section of this bridge at 

 right angles shows a rise of 5 feet, with a span of 25 feet. The springers at 

 this part are 15 inches deep, and the key-stone is 13 inches deep; on the 

 oblique section, or the elevation, the span is 37 feet 9 inches, and the rise 

 5 feet ; the springers are 24 inches deep, and the key-stone is 17 inches 

 deep. 



The straight part of the arch is formed vfith courses about 10 inches on 

 the soffit, and these are turned round in curved lines which are portions of 

 circles, the straight parts of the courses being then tangents, and they cut 

 the lines of the elevations at right angles, so that there is no more tendency 

 of the arch to sink at the elevation than would be the case with any elliptical 

 segment of similar dimensions worked in the ordinary way. The part of the 

 acute angle of the arch is formed with courses which converge from the ele- 

 vation to the abutments, on account of being arcs cutting the elevations at 

 right angles, and then becoming nearly taugential at the springing. The 

 curves for these courses were transferred from the development to the sheet- 

 ing, iu the same way as those for the Lancaster Canal Bridge, and the twist 

 of the beds was taken off full-sized sections of the arch, made in the direc- 

 tions of the converging lines of the extremities, so that at each of these 

 places the beds were worked as if for part of a true eUiptical arch, and the 

 beds between the points thus formed were worked off with curved rules found 

 from the development. After the masons got into the way of working this 

 kind of arch, they of their own accord preferred it to the complete skewed 

 arch. In brick work built in this way, it would be very easy to skew the 

 ends of a long arclnvay by having the bricks moulded to the curvature of 

 the key-course, as with a very little alteration they would fit any part of the 

 concentric courses, and a few tapered bricks would facilitate the fiUing up 

 of the fan-shaped part of the haunch of the acute angle. 



The communication was illustrated by several detailed drawings and a 

 model of the bridge, with schedules of the prices and cost of the woiks. 



