EEYIE"vfS — BEPOBT OK VICTORIA BEIDGE. 471 



think you will readily admit that I have given ample reasons in justification of the 

 extent of the abutments, bearing in mind that the form of construction contributes 

 more to their apparent magnitude than a cursory glance at their appearance upon 

 paper would justify one in supposing." 



Proceeding with a description of the masonry of the Piers and of 

 the details of their foundations, Mr. Stephenson continues : 



"Advantage has also been taken of the shallow depth of water, in constructing 

 the abutments, which are each 242 feet in length, and consist of masonry of the 

 same description as that on the piers, which I am about to describe, and, from their 

 being erected in such a small depth of water, their foundations do not require any 

 extraordinary means for their construction. 



The Foundations as you are aware are fortunately on solid rock, in no place at a 

 great depth below the summer level of the water in the river. 



Various methods of constructing the foundations suggested themselves and were 

 carefully considered, but without deciding upon any particular method of proceed- 

 ing, it was assumed that the diving bell, or such modifications of it on a larger 

 scale, as have been recently employed with great success in situations not very 

 dissimilar, would be the most expedient. The contractors, however, or rather the 

 Superintendent, Mr. Hodges, in conjunction with Mr. ltoss, after much considera- 

 tion on the spot, devised another system of laying the foundations, which was by 

 means of floating " Coffer-dams," so contrived that the usual difficulty in applying 

 coffer-dams for rock foundations would be, it was hoped, in a great measure obvia- 

 ted. When in Montreal, I examined a model of this contrivance and quite approved 

 of its application without feeling certain that it would materially reduce the expense 

 of construction below that of the system assumed to be adopted by Mr. Ross and 

 myself in making the estimate. In approving of the method proposed by Mr. 

 Hodges, I was actuated by the feeling that the Engineers would not be justified in 

 controlling the contractors in the adoption of such means as they might consider 

 most economical to themselves, so long as the soundness and stability of the work 

 were in no way affected. 



This new method has been hitherto acted upon with such modifications, as ex- 

 perience has suggested from time to time, during the progress of the work, and 

 although successfully, I learn from the contractors that experience has proved the 

 bed of the river to be far more irregular than was at first supposed, — presenting, 

 instead of tolerably uniform ledges of rock, large loose fragments which are strewed 

 about, and cause much inconvenience and delay. 



They are therefore necessitated to vary their mode of proceeding to meet these 

 new circumstances; and it may be stated, that all observations up to this time shew 

 the propriety, notwithstanding the difficulty with dams, of carrying the ashlar 

 masonry of the piers, do^vn to the solid rock — and that any attempt at obtaining 

 a permanent foundation by means of concrete, confined in " caissons " would be 

 utterly futile ; — however, if it were assumed to be practicable, there would be ex- 

 treme danger in trusting such a superstructure of masonry upon concrete, confined 

 in cast iron "caissons " above the bed of the river: indeed, considering the pe- 

 culiarities of the situation and the facts which have been ascertained, this mode 

 of forming foundations is the most inappropriate that can be suggested, as it 

 involves so many contingencies, that to calculate the extreme expense would be 

 utterly impossible. 



