246 CORRESPONDENCE OF GILBERT WHITE 



they are both true. But the annual increase in the Swallow 

 tribe, which are lost in Winter, affords unaccountable difficul- 

 ties 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 million, 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 : and i never heard that Swallows are increased 

 in any part of the Globe. We know that all the carnivorous 

 Birds drive off their 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 *, that yearly 

 nested on an Island of Hock 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, and ap- 

 pears here as the latest comer. I used to have many in my 

 Woods ; but since the long and severe Winter of SS i have 

 had very few. Is not this a presumptive proof of their tor- 

 pidity? & that they were destroyed by the severity of that 

 Season? — Your account of the 26 & 27 of March in 1777 was 

 felt here 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, and my Therm 1 " 

 sunk above 20 degrees in 3 or 4 hours. The greatest change 

 I have ever observed. — I find in 1776 Jan. 31. your Therm 1 " 

 sunk to 0. mine of Farenh' 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 



* [The name " Osprey " seems to have been formerly applied to the 

 Sea-Eagle (Haliaetus albkilla) as well as to what is now known as the 

 Osprey (Pandion haliaetus). 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.] 



