AND LOCALITY OF MUSC.& VOLITANTES. 385 



The details in the preceding pages may, therefore, be considered as establish- 

 ing the important fact, that Musca wlitantes have no connection whatever either 

 with Cataract or Amaurosis, and that they are nearly altogether harmless. This 

 result has been deduced by the aid of a recondite property of divergent light, 

 which has only been developed in our own day, and which seems to have no 

 bearing whatever of an utilitarian character. And this is but one of numerous 

 proofs which the progress of knowledge is daily accumulating, that the most ab- 

 stract and apparently transcendental truths in physical science will sooner or 

 later add their tribute to supply human wants, and alleviate human sufferings. 

 Nor has science performed one of the least important of her functions when she 

 enables us, either in our own case, or in that of others, to dispel those anxieties 

 and fears which are the necessary offspring of ignorance and error. 



ST LEONARD'S COLLEGE, ST ANDREWS, 

 March 4. 1843. 



the vitreous humour rather than in the aqueous ; but that he had been stopped by the difficulty of recon- 

 ciling this opinion with the viscosity of the vitreous humour. As the vitreous humour is perfectly fluid 

 within each cell, the viscosity here supposed being only apparent, no longer presents any difficulty. 



VOL. XV. PART HI. 5 L 



