Proceedings. XXlil. 
and had been gnawed through by rats. Both exhibited the 
marks of the teeth of the animals very plainly. One had been 
sent to him by Mr. R. Pelton, of Tunbridge Wells. The other 
specimen in the room had been brought by a member of the 
club (Mr. E. Straker). He passed the pieces of pipe round for 
inspection, and read the following letter as to one of them from 
Mr. Pelton :— 
68, Parade, Tunbridge Wells, March 23rd, 1879. 
Dear S1r,— It may possibly be interesting to the members of the 
Croydon Microscopical Club to see a piece of lead pipe gnawed 
through by rats, as described in the extract from Nature, at the foot 
of a letter in the Croydon Advertiser, signed H. M. Klaassen. 
The pipe from which this piece is taken runs along on a concrete 
floor at the basement of my house, and is of course exposed, although 
a wood flooring is above the concrete. During a severe frost a few 
winters ago the, cistern was found empty, and on opening the floor 
the water had escaped through the hole made by the rats in the piece 
of pipe I send herewith. It is possible that during the severe frost 
the usual supplies of water which the rats were in the habit of getting 
their drink from had frozen up, and as they say these animals get 
very desperate when thirsty, they must have had instinct strong 
enough to know that water was in the pipe, and attacked it 
accordingly. Two facts noticed were curious—tst, the almost entire 
absence of the lead filings round the hole made; 2nd, the largeness 
of the hole. Taking No. 2 first I may say the pipe was fully charged 
from a rather large cistern, and. consequently I conclude that the 
hole must have been small at first, and the water would probably 
then rush through and perhaps frighten these four-footed engineers 
away until the cistern emptied itself. When this was done they 
must have come back again, and probably tempted by the trickling 
of a little water at the bottom of the pipe, commenced gnawing until 
they made the hole large enough to get their noses in. As to the 
absence of the lead filings, some of them doubtless got washed away, 
some of them were around the hole and in the pipe, and I cannot but 
think that some of them were eaten; whether they were good for 
digestion or not you are a much better judge than myself. 
I am, &c., yours obediently, 
R. PELTON. 
—Dr. Carpenter went on to remark that rats had a great deal 
to do with the destruction of the atmospheric railway which 
used to run from Croydon to London. He explained the 
principle on which that railway was constructed, viz., the 
exhaustion of air from a so-called pneumatic tube, and stated 
that by the rats gnawing some of the leather the tube was no 
longer air-tight, and the carriages in consequence frequently 
came to a dead stop. 
Dr. Carpenter also exhibited a piece of the lower part of the 
trunk of alaburnum tree from the garden of the Rev. M. Farrar, 
of Shirley, in which a colony of Ants (Formica Umbrata ?) had 
formed their abode, and described shortly the history and habits 
