12 
The late Dr. Jenner 
appear conspicuous to the reader, but which I did not con- 
ceive myself justified in attempting. 
I have the honour to be, Sir, 
Your most obedient humble servant, 
Stone , near Berkeley, G. C. JENNER. 
May 29, 1823. 
To Sir Humphry Davy, Bart. 
President of the Royal Society, 
&c. &c. Sec. 
I. 
Jt is not my intention, in the following pages, to give a 
general history of the migration of birds. The order in 
which they appear and disappear, their respective habits, and 
many other observations, have been given with considerable 
accuracy by several naturalists, who have paid attention to 
this very curious subject. It is with a view of representing 
some facts, hitherto unnoticed, chiefly with respect to the 
cause, which excites the bird, at certain seasons of the year, 
to quit one country for another, that I communicate the 
following pages to this learned body. 
But before I proceed to state my observations on this head, 
it may be necessary to adduce some arguments first, in sup- 
port of the reality of migration, the fact itself not being gene- 
rally admitted ; and, secondly, against the hypothesis of a 
state of torpor, or what has been called the hibernating 
system. 
In the first place, the ability of birds to take immensely 
long flights, is proved by the observations of almost every 
person conversant with the seas. To the many instances 
already recorded, I shall add the following : 
My late nephew, Lieutenant Jenner, on his passage to 
