340 HISTORY OF CHRONOPHOTOGRAPHY. 



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

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

 velocity of this current itself can be varied without end. 



I 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 unequal 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 by the Smithsonian 

 Institution. These are numbered a and b, a being a form producing 

 very little eddy, while 1> (a form not noticeably different) produces a 

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

 tance and the delicacy of the method.] 



