1 JANUARY 1927, Page 17


A query on a problem in natural history reached me all the way from America. It seems that an American entomologist has been gauging the speed of flight in various South American creatures, and has come to the conclusion that a certain large fly, called cephenemia, moves at the rate of 14 miles a minute. Can this be true ? The story is classed by my correspondent in the variety " tall." Well, a dragon fly can dart in the air So quickly as to be nearly invisible. It is possible that there are jerks and jumps of flight over a foot or two of space that might work out at an incredible rate per hour. Some biologist, who fixed straws in a mole's run, calculated that the burrower moved as fast as a trotting horse ; but one suspects the accuracy of the measurements. So small an error looks so big when the scale is extended. However invisibly fast a fly moves, a pheasant would probably beat it over a half-mile course ; and recent investigations into the speed of birds' flight lowers rather than heightens old estimates. The aeroplane is quicker than the quickest bird ; and many migration flights, of which exalted estimates were once current, are made at an average speed of less than 50 miles an hour. Except in the case of stooping hawks, or where gravity or wind comes to the help of the wings, it is unlikely that any bird much exceeds 80 miles an hour. The South American fly is credited with just over 800 miles an hour !