412 On the Methods of laying 



each pier wider than necessary : this surplusage, when 

 muhiplied, became as great an evil as that which it was 

 intended to prevent. There is sufficient evidence to show, 

 that timber always kept under water is imperishable, and 

 that piles, if they are not undermined by an improper 

 action on (he bed of the river, have a stability superior to 

 that of masonry ; inasmuch as the masonry cannot have 

 that connexion with the part buried in the soil, by which 

 the stability of a structure subject to lateral pressure is in 

 some measure obtained : it is true that the weight of ma- 

 sonry may be a substitute for the want of connexion: but 

 that weight is obtained to a piled foundation after the 

 manner of our ancestors by the stone-work with which 

 they stuffed the interstices between the piles. It will be 

 said that the piles are exposed to the corroding effects of 

 friction from the passage of the water and the traffic: this 

 is an old argument advanced periodically by the mason, 

 and is best answered by those instances where this effect 

 has been prevented by means not less simple than easy : 

 it is an evil to which stone is equally liable, and it requires 

 similar precautions. 



There is an advantage in tidal rivers attached to the 

 methods of the emperor Claudius and St. Benezet, which 

 does not belong to the methods, by turning the water, by 

 cofferdams and by caissons; namely, each pier and founda- 

 tion, previously to the imposition of the arch, may be tried 

 by loading it with a greater weight than the intended su- 

 perstructure : a vessel of such a burthen may be floated 

 over the site of the pier at high water, and left to rest on 

 it when the water has ebbed. 



In the first and second childhood of architecture, the 

 same means are resorted to, to effect the works of art : 

 tyranny in the one case, and wealth in the other, generally 

 produce the same ends : in both states, great and solid 

 works are produced, and the easy mode of obtaining them 

 through a lavish expense of materials and labour naturally 

 supersedes others which require less means and more talent 

 and judgement : to these qualities in the middle state, when 

 materials and labour are less at the command of the pro- 

 jector, there is a necessity of applying. 



The method of laying piers of bridges dry by means of 

 cofferdams was the method of early times, and is the me- 

 thod in practice at present. It is well adapted to a period 

 when the labour and fortune of the subject are the uncon- 

 ditional property of the ruler, when means may be wanted 

 to absorb the overflowing plunder of conquest, to paralyse 



the 



