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PART II. 
For the Year 1760. 
XL. A Letter to the Honour able J. Th. Klein, 
Secretary to the City o/D^ntzic^frofn Mr. 
Peter Collinfon, F. R. S. concerning the 
Migration of Swallows . 
Read 1 M » rch 9, T not know which to admire moft 
175 * I in my dear friend Klein, his learning, 
or his judgment, in compiling fo many 
ingenious and inftru&ive books in natural hiftory. 
But I muft beg leave to diffent from my learned 
friend, in an article he takes great pains to eftablifh ; 
which is, that fwallows are not birds of paffage; but, 
at the time of their going away, retire under water, 
and live therein, all the winter. This I cannot com- 
prehend, being fo contrary to nature and reafon ; for as 
they cannot live in that hate, without fome degree of 
breathing, this requires the circulation of the blood, 
however weak and languid. Now, as refpiration is 
abfolutely neceffary for circulation, how is it poffible 
to be carried on for fo many months under water, 
without the rifque of fuffocation ? 
Vol. LI. O 0 o 
Befides, 
