266 Recent Progress in Sanitary Science. 



XXV. — Recent Progress in Sanitary Science. 



By ALBERT R. LEEDS. 



Read October 9th, 1876. 



The recent progress in Sanitary Science is the history of 

 our knowledge of what constitutes clean air, clean water, 

 clean food, and clean environments ; of our knowledge of 

 what is tilth in air, tilth in water, filth in food, and tilth in 

 our environments, whether it be tilth mineral, vegetable, or 

 animal ; and finally, of the means of preserving cleanliness 

 on the one hand, and of repressing tilthiness on the other. 

 The great factors in this progress therefore are, in the first 

 place, knowledge, a knowledge both comprehensive and ex- 

 haustive, and in the second place, a moral zeal, which shall 

 make that knowledge effective in increasing cleanliness and 

 preventing filth among men. The necessity of this kind of 

 knowledge is mostly due to the crowding of multitudes into 

 overgrown commercial communities ; and its development, 

 which is largely that of chemical science, is also dependent 

 upon the skill of the microscopist, the experience of the 

 medical practitioner, and the learning of the biologist, re- 

 quiring the colaboration of such various classes of savans as 

 are also found in great cities, — for its growth to perfection. 



The demands of sanitary science extend to the most re- 

 fined methods of chemical research, and hi}- under contribu- 

 tion some of the most obscure branches'of Natural History, 

 like that of Helminthology, sciences which, in their inception, 

 appeared to have little bearing on the daily wants of man- 

 kind ; and they even extend to the most abstruse researches 

 of biology, in matters pertaining to the generation of spores, 

 the development of ova, the growth of parasites, etc. In- 

 deed, the demand reaches far beyond the present powers of 

 scientific inquiry to supply ; and a more subtle analysis is 

 required of the chemist, a more searching scrutiny of the 

 microscopist, before questions can be answered, on the cor- 



