FOR GREAT BRITAIN AND IRELAND. 93 



freely, and transmit its pressure unimpaired to those 

 below it" 



" If, therefore, a pier could be so constructed that on the 

 abstraction of a stone at the bottom the whole vertical 

 section of masonry resting upon it should at once sink, so 

 as to fill up the void, the perfection of marine masonry 

 would be attained, because the lower courses would then 

 bear the unreduced weight of the upper, and would there- 

 fore be the less easily abstracted. The difficulty of 

 pulling out any stone would then be proportional to its 

 distance from the top of the wall." 



" In land architecture the whole structure is greatly 

 strengthened by the occasional insertion of long stones, 

 but in the sea, where each stone is assailed per se, the 

 stability of any horizontal course, if equally exposed 

 throughout, is measured by the stability of the smallest 

 stone in that course, and therefore, the more uniform the 

 size of the materials in each horizontal section of the work, 

 the better. It is of some moment that this should be 

 properly understood, and that it should be recollected, that 

 a pier equally exposed throughout its whole length is no 

 stronger than its weakest point wherever that may be" 



" We must beware then of importing into marine en- 

 gineering, as is too generally done, the laws and maxims 

 of house architecture with its vertical bond and its small 

 but carefully dressed face-stones. It matters not, indeed, 

 how rough the masonry of the face-work of a sea-wall be, 

 provided there are no protuberances large enough to offer 

 material resistance to the jet of water in front of the wall ; 

 and we have already pointed out the valuable effects of 

 keeping the beds rough. All the blocks should, however, 

 bed and joint fairly on each other, and no face pinnings or 

 small closers should on any account be allowed in the outer 



