On Vortex Motions. 125 



any animal it becomes at once evident to us that independ- 

 ently of the vital principle, which is beyond our reach, the 

 functions of motive parts are carried on upon the highest 

 mechanical principles — principles generally that we believe 

 to be more exact than it is possible to reproduce by art. Thus 

 we witness in the eye, with its back and front lens and its 

 adjustable stop, the perfection of the camera obscura ; further 

 in this organ the researches of Bol have shewn that the retina 

 absolutely receives and retains a picture of the objects placed 

 before it in a manner that is somewhat like our photographic 

 processes. So that here we have altogether a perfect mechan- 

 ical contrivance as well as a vital one. In like manner we 

 have part of the ear placed in sensitive equilibrium so as to be 

 motive to the small impulses of the air which we recognize as 

 sound. In like manner also the heart resembles, and really is, 

 & force pump to the artereal system, and in like manner also 

 we find the functions of all vital parts, so far as we can trace 

 them, following independently as it were of vitality, strictly 

 imechanical law. From this we may therefore argue that if 

 a vortex motion is a form of motion adapted to the vital 

 system such a form will in all probability be active within it. 



I will first endeavour to discuss vortex motion simply. Fol- 

 lowing my original experiments I find that only one form of 

 the motion of a fluid within a fluid, or a resisting medium, 

 assumes the condition of a free projectile ; and this form is 

 that which has been previously distinguished as a vortex 

 motion. Upon further investigation I have drawn the con- 

 clusion that this is the only form of motion in which one fluid 

 could move upon another or really upon any other body. In 

 carrying out my researches by a long series of experiments I 

 endeavoured to ascertain what were the conditions of motion 

 in natural fluid systems. These observations extend to the 

 greatest spaces and the smallest ; taking our great oceans, whose 

 currents we have mapped out on our naval charts, for the 

 large spaces ; and the terminal capillary vessels of the animal 

 body, as we may observe them under the microscope, for the 

 smallest. It is unnecessary to say that in these observations 

 it was in the smallest that there was the greatest difficulty in 

 tracing principles. 



[Mr. Stanley then proceeded to exhibit a series of experi- 

 ments illustrative of vortex motion in liquid and aerial fluids 

 and to describe them, and he referred his hearers for further 

 information to his work on " Fluids," now in our library, and 

 especially with regard to the phenomenon of the vortex rings, 

 and then proceeded with the more special subject of his paper, 

 viz.: — The possibility of vortex motions being active in vital 

 systems]. 



