ISO ON THE CLASSIFICATION OF BIRDS. 
external crack, however, is so narrow, that we could 
not at first be persuaded there was sufficient room for a 
bird to enter : wishing, however, to ascertain the fact, 
we endeavoured to get in tlie fore finger and thumb, 
hut (]uickly withdrew them upon hearing a loud and 
determined hissing noise, exactly like that of a serpent ; 
and such we liegan to fancy was the real inhabitant, 
until, retiring to a sliort distance, we presently saw one 
of the parents fly into the crack and soon emerge 
again. To show that the laws of nature in regard to 
niditication are as strongly implanted in birds as are 
their other instincts and habits, we shall here relate 
another anecdote of the same species, which places this 
fact in a singularly strong light. The pump in our 
garden has an outer frame work of wood, the top being 
roof-shaped, and lifting on and off, in order the more 
readily to facilitate its repair. The spring of the year 
1 832 being rather wet, the pump was not used for some 
few weeks ; the weather, however, soon became dry, and 
on trying the pump, and finding great obstruction, we 
removetl the cover, which had only been half put on, 
in order to ascertain the cause : this was at once appa- 
rent, for the cylinder was completely choked up with 
hay, moss, and feathers, all the materials, in short, and in 
great quantity, for a nest ; and upon getting these out, 
five or six eggs were found of the blue titmouse. Sur- 
prised at the oddity of the bird in selecting such a situ- 
ation for its nest, we cleared the jiuinp, and concluded 
the affair was settled. But, no. Three or four days 
after, upon attempting to get water again, the pump 
was as much obstructed as before ; two or three hand- 
fuls of hay and moss were again taken out of the cylin- 
der, and the pump was again used ; before, however, 
the same period had elapsed, it became again choked, 
and, for the third time, it was again cleared of even more 
litter than before. Now it was quite evident, on the 
two last occasions, that the birds continued, with un- 
exampled perseverance, to bring fresh materials as fast 
as those they had deposited became wet; for, after the 
