UNCLE IN ENGLAND. 255 



Brunei had himself stated to a friend of his, that 

 it was from the operations of this worm that 

 he had borrowed the method which has been 

 adopted in forming the tunnel under the Thames. 



Mr. Brunei observed that the teredo's head is 

 covered with a strong armour, through a little 

 hole in which it perforates the wood first in one 

 direction and then in another, till the arched 

 way is complete ; when it daubs both roof and 

 sides with a kind of varnish. In like manner,, 

 Mr. B. conducts his operations in the tunnel; 

 removing the ground in front, through the small 

 apertures of a strong iron frame, which he calls 

 the shield, in imitation of the teredo 1 s armour; 

 and then constructing a circular arch of brick- 

 work, with strong cement, so as to resist the ut- 

 most pressure of the water. The shield is then 

 moved forward nine inches (the length of a 

 brick), a fresh ring of brick-work is built, and a 

 fresh portion of ground is excavated. 



This curious anecdote led to another of the 

 same nature, an ingenious contrivance bor- 

 rowed from a lobster's tail. On the other side 

 of the Clyde, opposite the city of Glasgow, 

 there was abundance of fine water, which it was 

 desirable to convey across the river for the use of 

 the inhabitants ; but so as not to interfere with 

 the shipping, and not to be contaminated with 

 the salt water. Mr. Watt, the celebrated engi- 

 neer, undertook to carry it in iron pipes fitted one 



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