no 



The Irish Naturalist. 



September, 



it was still plainly visible to me owing to the clear evening, it vanished 

 utterly and instantly just as if it had flown into the rather iow overhanging 

 clouds, some of which rested against the Dublin Mountains at an altitude 

 of about 1, 800 feet. Except for a few cloudy patches the sky was clear 

 and blue and the time few minutes to 10 p.m., summer time, i.e., about 

 8.30 p.m. " sun time." Prooably it was the fairly stift" westerly breeze 

 that made the bat's vertical ascent possible. I have never seen a bat 

 behave in such a manner before ; but, perhaps, this is due to want of 

 observation. Can any one suggest what its objective was ? 



A. W. Stelfox. 



Rathgar. 



As Mr. Stelfox has kindly shown me his interesting note, I think I 

 should add that I have on three occasions been witness to a singular 

 ascending flight on the part of the same species of bat — for it is quite 

 obvious from Mr. Stelfox's description that the subject of his note was 

 the Hairy-armed Bat [Nyctalus Leisleri), our largest Irish species, which 

 is generally the first to quit its retreat in the evening, and may often be 

 observed flying in company with the swifts, as Mr. Stelfox describes. 



At Ballyhyland, where this bat is not nearly so plentiful as it is near 

 Dublin, I was fortunate in having one of its sleeping places from which 

 Hairy-armed Bats could be seen taking flight any summer evening I 

 cared to watch for a period of twenty years (1900-1919 inclusive). During 

 a part of every summer the bats lived gregariously in this retreat (an old 

 ash-tree), and their custom on leaving it was- to fly away for some distance 

 at a fairly low level ; but on all occasions on which I saw the ascending 

 flight it was performed by a solitary bat, living in a retreat of its own 

 after the summer assemblage had broken up. 



As the notes I took are from 15 to 17 years old, I think I am safest 

 in quoting them as taken down at the time. 



(1) September 15th, 1904. — Hairy-armed Bat flew from the old ash 

 this evening at 6.17 (minute of sunset), and went very high in the air, 

 almost like a Lark. The evening was dark and damp, with a drizzling 

 rain. 



(2) September i6th, 1904. — The Hairy-armed Bat flew this evening 

 at 6.5 p.m., 10 minutes before sunset. Again went up very high, and 

 was kept in sight for ih minutes after quitting ash. The day, like 

 yesterday, was wet with thick drizzling rain. 



(3) October 4th, 1906. — The first Hairy-armed Bat came out at 5.42, 

 9 minutes after sunset, and went zig-zagging up into the air till out of 

 sight — this occupied i.^ minutes. (See notes for September 15th and 

 1 6th, 1904, when bat went up exactly the same way, and on all three 

 occasions the evening was thick with drizzling rain). 



As it is only in the last of these three notes that I use the expression 

 " zig-zagging," I have to trust my memorj'^ on the question whether the 

 ascents seen in September, 1904, were spiral, zigzag, or perpendicular, 



