120 The Rev. F. W. Hope on Limnoria. 



bury them in the sea : but in a short time, from abrasion, the piles 

 are robbed of this coating, and become perforated by the Limnorice. 



There is an announcement in the public Journals, that Mr. Ste- 

 venson has discovered a varnish capable of protecting wood from the 

 attacks of this destructive pest. "What this varnish may be I am at 

 a loss to conjecture ; I only hope that Mr. Stevenson ■will shortly 

 make his discovery known, and as publicly as possible, as he may be 

 the means of saving the wood-work of our floodgates, timber- 

 bridges, chain-piers and docks from inevitable destruction. 



At the chain-pier at Southend in Essex the piles are daubed over 

 with gas tar ; and from inquiries made on the sjoot from the work- 

 men employed, I found that there exists a general belief that where 

 common tar fails, gas tar succeeds, the insects, as the workmen 

 assert, not liking its taste. 



Both the varnish of Mr. Stevenson and the gas tar may succeed 

 for a time ; abrasion, however, will at length remove them : would 

 it not therefore be possible, by means of perforated iron pipes running 

 through the centre of the piles, occasionally to supply liquidated tar, 

 and so keep up this gaseous influence .'' The expense of the pipes 

 would probably be too great. It is ascertained that the Limnorics 

 attack neither the bottoms of ships, nor fresh-tarred piles newly placed 

 in the sea, partly, perhaps, as it requires time for abrasion to take 

 place, and partly as the eff^ect of the tar is not neutralized by salt 

 water. Tar appears to be an antidote : gas tar may be more effica- 

 cious ; and as the oxidation of iron is effective for a certain period, 

 probably by uniting two or more of these, we may preserve the piles 

 for a longer period than has hitherto been done. In the sea I would 

 form a bed of gas lime, next add a thick stratum of gas tar, and then 

 drive the piles into it, coating them well over with gas tar before- 

 hand : by these means some good might be eff'ected. By nailing also 

 to the piles portions of honeycombed wrought-iron gas pipes, (which 

 might be purchased, I imagine, for a mere trifle,) the gaseous taste 

 might be kept up. Another remedy might be tried by saturating the 

 piles with strong solutions of corrosive sublimate. Moreover, should 

 the spirit of caoutchouc (or Indian-rubber) be found eventually to be 

 disliked by the Limnorice, we shall then have a cheap and easy remedy. 

 So long as ivood is used in the bedding of our marine i^ublic works, 

 so long the annual loss must be great. As in five or six years the 

 wooden piles become perforated and nearly useless, might it not be 

 possible, by means of cast-iron hollow pipes filled with cement, and 

 coated with a varnish externally, to make them last for twenty or 

 thirty years ? As this is a mere matter of calculation as to expense, 

 I do not wish to enter upon it ; any observations which may tend to 



