236 INDIRECT INJURIES CAUSED BY INSECTS. 



the North Pier about three years since, which is now 

 crumbled away to less than an inch in thickness — in fact, 

 deducting the space occupied by the cells which cover 

 both surfaces as closely as possible, barely half an inch 

 of solid wood is left ; and though its progress is slower 

 in oak, that wood is equally liable to be attacked by it. 

 — If this insect were easily introduced to new stations, 

 it might soon prove as destructive to our jetties as the 

 Teredo navalis to those of Holland, and induce the ne- 

 cessity of substituting stone for wood universally, what- 

 ever the expense : but happily it seems endowed with 

 very limited powers of migration; for, though it has 

 spread along both the South and East Piers of Bridling- 

 ton harbour, it has not yet, as Mr. Lutwidge informs 

 me, reached the dolphin nor an insulated jetty within 

 the harbour. — No other remedy against its attacks is 

 known than that of keeping the wood free from salt- 

 water for three or four days, in which case it dies ; but 

 this method it is obvious can be rarely applicable a . 



How dear are their books, their cabinets of the va- 

 rious productions of nature, and their collections of 

 prints and other Avorks of art and science, to the learned, 



a In order to ascertain how far pure sea water is essential to this 

 insect, and consequently what danger exists of its being introduced 

 into the wood-work of our docks and piers communicating with our 

 salt-water rivers, as at Hull, Liverpool, Bristol, Ipswich, &c, where 

 it might be far more injurious than even on the coast, I have, since 

 December 15th 1815, when Mr. Lutwidge was so kind as to furnish 

 me with a piece of oak full of the insects in a living state, poured a 

 not very strong solution of common salt over the wood, everj r other 

 day, so as to keep the insects constantly wet. On examining it this 

 day (Feb. 5th 1816) I found them alive ,- and, what seems to prove 

 them in as good health as in their natural habitat, numbers have esta- 

 blished themselves in a piece of fir-wood which I nailed to the oak, and 

 have in this short interval, and in winter too, bored many cells in it. 



