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HARDWICKE'S SCIENCE-GOSSIP. 



montine reading-lamp, and also with the bull's-eye 

 condenser, arranged to throw its rays on the 

 mirror. Ralph H. Westropp, B.A., T.C.D. 



Attyflin Park. 



WINDHOVERING. 



I HAVE been reading lately the " Reign of Law " 

 by the Duke of Argyll, and in the chapter 

 on the machinery of flight of birds, felt greatly 

 delighted with the observations and suggestions. 

 There cannot, I should think, be a doubt that the 

 explanations given by him are correct and true 

 — that just as a man, in swimming, advances on 

 the sides of a wedge of water by approximating his 

 legs, so a bird progresses, in flying, by squeezing 

 backwards the wedge of air embraced by every beat 

 of the wings, the feathers being so arranged, that 

 motion forward must be the necessary result of 

 every stroke, without any special effort on the part 

 of the bird ; but when his Grace goes on to describe 

 the wonderful power of windhovering possessed by 

 some birds, although I dothiuk his exposition good, 

 I believe it is a power given to a much greater 

 number of birds than he supposes. " No bird can 

 exercise this power which is not provided with 

 wings large enough, long enough, and powerful 

 enough, to sustain its weight with ease, and without 

 violent exertion." "Birds with superabundant 

 sustaining power, and long sharp wings, have 

 nothing to do but to diminish the length of stroke, 

 and direct it off the perpendicular at such an angle 

 as will bring all the forces bearing upon their body to 

 an exact balance, and they will thenremain stationary 

 at a fixed point in the air." From the remaining 

 context I am led to suppose his Grace believes that 

 only birds with long sharp wings — those with the 

 first or second primary feathers longest— are invested 

 with this power ; but the Whinchat is a capital 

 windhoverer, and so are the TVhitethroat and Wag- 

 tail. I have seen the Spotted Fly-catcher perform 

 the evolutions, and lately 7 , to my great delight, a 

 Blackbird, in its efforts to catch a humble bee — a 

 chase that lasted, perhaps, a minute. If all these 

 round-winged birds can, on occasion, perform this 

 trick of flight, the thought is naturally suggested, 

 why may not every bird, whose time is chiefly spent 

 in the air, possess this power, if it choose to exercise 

 it ; for has not God given to all birds of this class 

 a superabundant sustaining beat of wing? Let us 

 take the birds above mentioned and compare their 

 measurements with those of the Kestrel, the beau 

 ideal of a hoverer. The length of the Whinchat is 

 5 inches, the stretch of wings 9£ inches ; the White- 

 throat, length 54 inches, stretch of wings 84 inches ; 

 the Wagtail, length 74 inches, stretch of wings 12 

 inches ; the Spotted Flycatcher, length 54 inches, 

 stretch of wings 9 inches ; the Blackbird, length 



104 inches, stretch of wings 16 inches ; the Kestrel, 

 length 15 inches, stretch of wings 27 inches. Now, 

 if mere stretch of wing would decide this matter, 

 we should, a priori, suppose that the Whinchat 

 would be a better windhoverer than the Kestrel, 

 and that most probably the Blackbird could not 

 hover at all ; but as such is not the fact, it behoves 

 us to search for a further reason for the exercise of 

 this power than that given by the Duke ; and I 

 would suggest that the expanded tail is the chief 

 agent. When the Kestrel is searching a district, 

 his body appears almost upright, his tail spread to 

 the utmost and bent forwards, and his wings half- 

 shut and quivering. Whether it has the power of 

 altering the position of the secondary feathers 

 with every beat of the wing, I know not; but cer- 

 tainly the upright position of the body would make 

 a large part of every wave of air created by the 

 wing-stroke beat against the expanded tail, and 

 neutralize, to the necessary extent, the forward 

 motion of the remainder of the wave passing back- 

 wards. I cannot, therefore, but believe, that almost 

 any bird strong on the wing, and with a good tail, 

 could windhover if it liked, or if it were necessary 

 for the successful search after daily food. 



Joseph Dbew. 



CORNISH SUCKER. 



AS far as the experience of three years will 

 allow me to judge, I should say that the 

 Lepidogaster cornubiensis is decidedly a rare fish, 

 although, as we might suppose from- its name, it 

 may be found more frequently in Cornwall than 

 elsewhere. Doubtless, like most other fishes, it 

 moves about in shoals ; for when one is found it 

 will not be necessary to search very far for a 

 second specimen. This fact was particularly im- 

 pressed upon me two summers ago, at Halleine, 

 the beach of the village of Trenarven ; for on that 

 occasion it would have been easy to have filled a 

 large basket in a very short time with these strange 

 little fishes, as almost every stone covered one, two, 

 or more of them. I have often, since then, visited 

 the same beach and turned over and over the same 

 stones, but always unsuccessfully. I caught and 

 compared about a dozen altogether, and found them 

 about the same size— one perhaps appeared plumper 

 than another, and the eyes of one larger than the 

 eyes of another, and the sucking-disks formed by 

 the pectoral and ventral fins were larger in some 

 than others ; but the length was almost uniformly 

 the same,— about two inches : so that, doubtless, 

 they were all of the same age. My friend aud I 

 got a great deal of amusement out of our catch by 

 making them adhere in all sorts of comical positions ; 

 and those of my readers who have ever seen one of 

 firse odd-looking creatures will quite comprehend 

 me possibility of our mirth. Joseph Drew. 



