26 ZOOPRAXOGRAPHY 



edging the skill, patience and energy which these gen- 

 tlemen exhibited in their respective fields of labor. 



Although the one six-thousandth part of a second 

 was the duration of the most rapid exposure made in 

 this investigation, it is by no means the limit of 

 mechanically effected photographic exposures, nor does 

 the one-sixtieth part of a second approach the limit 

 of time intervals. Marey, in his remarkable physiologi- 

 cal investigations, has recently made successive expos- 

 ures with far less intervals of time; and the author has 

 devised, and when a relaxation of the demands upon 

 his time permit, will use an apparatus which will 

 photograph twenty consecutive phases of a single 

 vibration of the wing of an insect; even assuming as 

 correct a quotation from NicTiolson'' s Journal by Petti- 

 grew in his work on Animal Locomotion that a com- 

 mon house fly will make during flight seven hundred 

 and fifty vibrations of its wings in a second of time, a 

 number probably far in excess of the reality. 



The ingenious gentlemen who are persistently en- 

 deavoring to overcome the obstacles in the construc- 

 tion of an apparatus for aerial navigation, will perhaps 

 some day be awakened by the fact that the only suc- 

 cessful method of propulsion will be found in the action 

 of the wing of an insect. 



We will now resume the subject proper of this 

 monograph. 



It is impossible within its limits to trace the history 

 of the art of delineating animals in motion, or to 

 illustrate it with examples of the truthful impressions of 

 the primitive Artists, or of the imaginative and erro- 

 neous conceptions of many of those of modern times. 



