132 



ANIMAL LOCOMOTION. 



Some of my readers will probably infer from the foregoing, 

 that the figure-of-8 curves formed along the anterior and pos- 

 terior margins of the pinions are not necessary to flight, since 

 the tips and posterior margins of the wings may be removed 

 without destroying it. To such I reply, that the wings are 

 flexible, elastic, and composed of a congeries of curved sur- 

 faces, and that so long as a portion of them remains, they 

 form, or tend to form, figure-of-8 curves in every direction. 



Captain F. W. Hutton, in a recent paper " On the Flight 

 of Birds" (/fc, April 1872), refers to some of the experi- 

 ments detailed above, and endeavours to frame a theory of 

 flight, which difl'ers in some respects from my own. His 

 remarks are singularly inappropriate, and illustrate in a forci- 

 ble manner the old adage, " A little knowledge is a danger- 

 ous thing." If Captain Hutton had taken the trouble to look 

 into my memoir " On the Physiology of Wings,'* communi- 

 cated to the Eoyal Society of Edinburgh, on the 2d of August 

 1870,^ fifteen months before his own paper was written, there 

 is reason to believe he would have arrived at very diff'erent 

 conclusions. Assuredly he would not have ventured to make 

 the rash statements he has made, the more especially as he 

 attempts to controvert my views, which are based upon ana- 

 tomical research and experiment, without making any dis- 

 sections or experiments of his own. 



The Wing area decreases as the Size and Weight of the Volant 

 Animal increases. — While, as explained in the last section, no 

 definite relation exists between the weight of a flying animal 

 and the size of its flying surfaces, there being, as stated, heavy 

 bodied and small- winged insects, bats, and birds, and the con- 

 verse ; and while, as I have shown by experiment, flight is 

 possible within a wide range, the wings being, as a rule, in 

 excess of what are required for the purposes of flight ; still 

 ib appears, from the researches of M. de Lucy, that there is a 

 geueral law, to the eff'ect that the larger the volant animal 

 the smaller by comparison are its flying surfaces. The exist- 

 ence of such a law is very encouraging as far as artificial 



" On the Physiology of Wings, being an Analysis of the Movements by 

 which Flight is produced in the Insect, Bat, and Bird." — Trans. Roy. Soc. of 

 Edinburgh, vol. xxvi. 



