340 HISTORY OF CHRONOPHOTOGRAl'HY. 



We can not onimierate all the numerous applications of this method, 

 since the form and dimensions of the bodies in the air current and the 

 velocit}" of this current itself can be varied without end. 



1 have never observed the "jumps" noted by Mr. Mach, as making 

 the current deviate from one side to another. These ""jumps" might 

 possibly be due to the unec{ual temperature of the moving air. It 

 may be regarded, I think, as a proof of the precision of my method 

 that if an experiment is repeated under the same conditions the 

 observed images are identical and superposable on each other. 



I believe I may add that this method will give the mechanical solu- 

 tion of many problems relating to propelling apparatus, fluids, and 

 questions of ventilation, etc. 



[To Mr. Marey's interesting article we add two other illustrations 

 from his own experiments, since received from him l>y the Smithsonian 

 Institution. These are numbered a and h^ a being a form producing 

 very little edd}^ while l> (a form not noticeably diflerent) produces a 

 very great one. These seem to be well calculated to show the impor- 

 tance and the delicacy of the method.] 



