MIRROR ON A FLY'S WING

New Zealand Herald, Volume LXXV, Issue 23181, 29 October 1938, Page 9 (Supplement)

MIRROR ON A FLY'S WING

J)R. HOLLICK, the naturalist, fixes mirrors on a fly's wings. This is the very newest way of holding the mirror up to Nature. The mirrors are very tiny, the task of fixing them is one asking for the utmost delicacy and patience, but when in position they tell Dr. Hollick how the wings are moving. The fly is suspended in a wind tunnel, and the light thrown on the mirrors is reflected and recorded on a photographic film. The actual movement is thus magnified and the vibrations of the wings can be measured and counted. In this way some exact knowledge of the flight of a fly may be forthcoming in place of the rather rash statements about its sjwcd which have been made from time to time. Lately it was said, and believed by some naturalists who should have known better, that a

particular kind of deer fly in America attained a speed of 800 miles an hour in short bursts. v This was easily shown to ba ridiculous by those who investigated the matter scientifically, and the speed was afterwards redqced to 25 miles au hour, which is probably as fast as any insect can move. Other experimenters have tried to calculate tho speed of insects by lightly twisting fine silk threads about their bodies before letting them buzz off. This seems a hampering and rather clumsy way of dealing with the problem, and Dr. Etollick's method, though it needs very complicated apparatus, is better becausS if the period of vibration of the wings can bo arrived at, tho time of flight and tho rate of travel can be calculated from it. But the mirrors have to be no bigger than a bee's knee.