5024 TuE Zoo_octst—Auvecust, 1876. 
we see the result in the long, measured sweep of the ocean-bird’s wing 
and the rapid strokes of the others. This is in strict accordance with a 
mechanical law respecting the ratio between time of motion and distance 
traversed. Given, say, a hummer’s wing two inches from flexure to tip of 
first primary, and one inch from flexure to shoulder-joint; this would make 
the point of the wing describe an arc of a circle with a radius of three inches ; 
and a certain amount of muscular contraction effects this in a certain time. 
Now, lengthen fore-arm and upper-arm till they are each about two inches 
long, which would be something like the relative lengths in an albatross’ 
wing; this would make the point of the wing move in an are of a circle 
with a radius of ten inches. Now, the muscular force remaining the same, 
it is evident that the point of the wing could not move through this much 
larger arc in the same time; i.e., the wing-strokes would be necessarily 
slower. It is interesting to observe how, in some other birds, a similar 
result is brought about by different means. In a partridge, for instance, 
without special shortening of upper-arm or fore-arm, the longest quill-feather 
is brought nearer the body by the roundness of the wing, that is, the 
successive shortening of several outer primaries; and this bird, as is well 
known, makes correspondingly more rapid wing-beats, and vigorous, whirring 
flight. In the humming-bird, the quickness of the wing-vibration reaches 
the maximum; so rapid is it that the eye cannot follow the strokes, but 
merely perceives a film on each side of the body. The flight of the bird is 
also the most rapid; frequently the eye cannot follow the bird itself. It is 
almost needless to add that the peculiar sound, from which the family takes 
its English name, is not vocal, but produced by the wings, just as it is in 
the case of so many insects.” 
We shall probably return again to the ‘ Birds of the North- 
West. There are some amusing life-pictures of various Totanida, 
a group of birds largely represented in America, which we should 
be glad to make extracts from. Tor the present we bid Dr. Coues 
farewell; our difficulty has been in so much that is interesting to 
select passages for quotation. 
Morray A. MATHEW. 
A few Ornithological Notes from Guernsey and some of the other 
Channel Islands, from the 3rd to the 19th of June, 1876. 
By Ceciz Suiru, Esq., F.L.S. 
First amongst the birds to be mentioned is the Iceland falcon, 
recorded by Mr. Couch in the June number of the ‘ Zoologist’ for 
