138 
they are both true. But the annual increase in the Swallow tribe, 
which are lost in Winter affords unaccountable difficulties to be 
cleared. I have had 4 pair attending my house as many years as 
i can remember. If these produce two broods of 5 young, you see, 
Sir, one pair only, will in 7 years produce above half a milion, 
559870 birds: yet the number every Spring appears the same. 
If both broods are destroyed, surely the old birds would be lessened 
by accidents, so as to be perceptible. If the early, or the latter brood 
is preserved, you see the next Spring Birds will be as 5 to 2, if all 
the old Birds are lost : & i never heard that Swallows are increased 
in any part of the Globe. We know that all the carnivorous 
Birds drive off them young as soon as they are able to provide for 
themselves ; & i conclude that fish-eating Birds do the same : for 
when i was on the charming Lake of Killarny, i was told that 
was the case of a pair of Ospreys, 7 that yearly nested on an Island 
of Bock in that Lake. But we cannot suppose the Swallow tribe 
can fear the want of provision. S r , you know the Fern Owl is one 
of the Spring Birds, & appears here as the latest comer. I used 
to have many in my Woods; but since the long & severe Winter 
of 88 i have had very few. Is not this a presumptive proof of 
their torpidity 1 & that they were destroyed by the severity of that 
Season! — Your account oftlie 26 &27 of March in 1777 wasfelthere 
in Lat. 52.45°. but no Swallows appeared. The 27 th - was insufferably 
hot, with a S. W. Wind ; which changed in the afternoon to N.E. 
with a thick Sea-hase, & my ThernT sunk above 20 degrees in 3 or 
4 hours. The greatest change i have ever observed. — I find in 
1776 Jan. 31. your ThernT- sunk to 0. mine of FarenlY was at 16. 
& in 1784 Dec. 10. when your Dollands was 1. below 0, mine was 
but at 10. The coldest Air I have measured was Jan. 19. in 1767. 
when it was down to 1. I take the liberty to tell you this, as it 
possibly may be entertaining to you to see the difference of less 
than 2 Degrees of Lat. 
Sir, when you print a 2' 1 Edition, (which the merit of your Book 
7 The name “Osprey” seems to have been formerly applied to the Sea- 
Eagle (Ealiaetus albicilla) as well as to what is now known as the Osprey 
(Pandion hciliaetus). Thompson states (Nat. Hist. Ireland, i. p. 29 note) 
that no proof of the latter’s building either at Killarney or elsewhere in 
Ireland had to his knowledge yet been recorded, and it is therefore likely 
that the species spoken of in the text was the former. — A.N. 
