458 Remarks on the 
mals, which are actually known to pass the 
cold season in a torpid condition. 
After making the foregoing remarks on 
-torpidity, I come to certain facts, which are 
far from favouring the supposed analogy of 
those animals which are known to be lethar- 
gic in winter, and our summer visitors of the 
feathered tribe. Birds of this description 
are very numerous in this part of the world 
at the time of their disappearance ; from 
which circumstance it is reasonable to con- 
clude, that if they take up their winter abode 
near the surface of the earth, they would be 
frequently found in the cold season; which 
is the case with bats, field-mice, and hedge- 
hogs. Though discoveries of this kind are 
mentioned by various authors, the uncom- 
monness of the circumstance obliges the 
advocates of torpidity to dispose of the pe- 
riodical birds during winter, in places which 
are inaccessible to men, such as the vaults of 
profound caverns or the bottoms of deep 
lakes. My objections to this opinion, are 
derived from certain facts respecting the tem- 
perature of places situated at great depths © 
below the surface of the land and water. 
Every place on the globe has an invariable 
temperature peculiar to itself, which cannot be 
