Dr Coldstream on tlie Structure and 



(four years after their fixture), found to have been so very 

 much destroyed by the limnoria, as to be useless, and, at great 

 expense, were removed and replaced by new ones. These piles 

 were originally twelve inches square, or forty-eight inches in 

 circumference ; and in the course of the few years that elapsed 

 before their destruction became matter of enquiry, the girth of 

 some was reduced to six inches, so that the least force was suf- 

 ficient to break them through. On this occasion, the means of 

 preserving wood from the attacks of so destructive an animal 

 formed the subject of general attention amongst engineers and 

 inen of science ; and many plans were proposed and tried. Of 

 these, after two or three years' proof, none was found to answer 

 so well as the covering of the whole surface of the pile, from the 

 place where it met the bottom of the sea, to within a foot or two 

 of mean high- water mark, with broad-headed iron nails, technically 

 called scupper-nails, set close together. Four years afterwards, 

 when it was proposed to extend the pier of Leith on wooden 

 piles, the same plan was adopted, at an expense, for the wbqje 

 pier, of about L. 1000 ; the total cost of the pier being 

 L. 30,000. It is satisfactory to know, that, although nearly 

 four years have now elapsed since the first piles of this elegant 

 erection were driven, the limnoria has not effecte3 a lodgement 

 in any of those protected by the iron nails ; while several other 

 pieces of wood attached to them, (such as the supports of some 

 hand-rails, and, in particular, the wood- work of a wear running 

 out from the end of the pier to the length of a few hundred 

 feet) are already much destroyed. Some of the last- mentioned 

 timber, which had been originally about two inches in thickness, 

 is almost entirely eaten away. It is worthy of remark, that this 

 is the case, even in the immediate vicinity of iron-bolts and 

 nails ; the borings of the animal sometimes approach these 

 within a few lines, yet the piles defended by the nails are not 

 touched. This does not appear to depend altogether upon these 

 last becoming encased with a thick crvist of the pxi|[}e of iron, 

 impervious to their mandibles; for there are some piles on which 

 this crust has not been formed, close to the wood, tenanted by 

 the lirpnori^, >vhich do not exhibit the least vestige pf its 

 attacks. 



