Marvels of the Universe 995 
riddled with the tunnels of the Ship-worm that their collapse and the consequent flooding of the 
country was feared. No really satisfactory methods of preventing these attacks is known, though 
a certain amount of success was obtained by steeping timbers in a solution of ferric oxide before 
their immersion in the sea. 
It would be unfair, how- 
ever, to dwell on the evil 
work of the Ship-worm with- 
out mentioning that a great 
engineering feat was once 
successfully accomplished by 
their aid. In the adjoining 
photo you will see that the 
bore of the Teredo is lined 
with a thick coating of porce- 
lain; some of this has been 
broken away and shows the 
hollow channelling, but in 
certain places the covering 
still remains, and it is quite 
thick, and, for the size of the 
creature that made it, ex- 
ceedingly strong. The method 
by which the Teredo obtains 
this result was once carefully 
watched by Sir Isambard 
Brunel, and it is said that 
the same plan of working was 
adopted by him in the con- 
struction of the Thames Tun- 
nel. He found that the Teredo 
bored out only a small piece 
of tunnelling at a time and 
then set to work to plaster 
the sides well with a kind of 
cement. Brunel therefore ar- 
ranged that only a few feet 
of tunnel should be excavated 
at a time, and that it should 
be firmly bricked round before 
the boring was carried further. 
It is to this method that the rake 
; THE SHIP-WORM. 
great engineer owed the suc- Burrows cf the Ship-worm in wood. Note how they are lined with cement— 
cess of the enterprise, and it the prototype of man-made tunnels. 
was due in a great measure to the application of the hints derived from watching the tactics of 
the Ship-worm. 
We must now turn our attention to the creature itself, and find out all we can of its family and 
structure. First of all, we must rid ourselves of the idea that this worm is a worm in very truth, 
It is a mollusc and belongs to the great family of bivalves and is intimately connected with the 
Piddocks, which have been described in the article on Rock-borers (see page 696). In fact, it might 
72 
