that thio nound was eornetimes produced rather 
than incidentally! or, to be more precise, that the birds 
sometimee extended arui be t their vdnge for the express 
purpose of *nal:lrig the sound* I now doubt the accuracy of 
« 
those earlier observations, for during the past week I 
have never seen, the birds flutter their wings efficiently 
to produce the rumbll:-^ vifithout at the esuoe tl.ie changing 
their positions or at least their foothold* 
The bird which I took to be the emale usually 
went directly or very quickly to the nest and alighted on 
its outer rim where she would sometimes sit for hours, 
with her bill nearly t uchlng the walls of the chimney* 
The- tips of her folded ifdngs extended out behind, half way 
across the flue lookir^, when viewed from below, like two 
slender, curved, converging lines drawn on the field of 
bright light that entered the dhlimey from above. Her 
mate opent ?nuch of his idle time clinging to the chimney 
just above the nest, but fjometimes during the day, and 
Invnriably at the near approach of he vsould crowd 
himself into the nest by his partner’s side, taking exactly 
the same position ishloh she habitually assumed. Long after 
dark, in fact usually up to the time -sdien we went to bed, 
we heard the birds fluttering their wings dr calling to 
one another at frequent intervals. Tiieir vocal notes 
were the same as those which they use whe;t flying about 
by day but their twittering, when henrd at ni^t la this 
chimney, seemed to me infinitely more tender and musical 
