1889-90.] NATURAL HISTORY OF GROUND WATERS. 149 



SOxME POINTS IN THE NATURAL HISTORY OF GROUND 



WATERS. 



By p. H. Bryce, M.A., M.D. 



(Read ist March 18 go.) 



To the President and Members of the Canadian Institute : 



Gentlemen, — In choosing a title for my paper, while recognizing fully 

 how much has been said and written regarding drinking water, I have 

 felt that the enormous importance which attaches to it as one of the 

 necessaries of life demands that public attention should repeatedly be 

 drawn not only to the sources from whence pure and wholesome sup- 

 plies are obtained, but also to the dangers which are associated with its 

 pollution, and the ways by which this is brought about. 



I propose in this paper to indicate briefly the physical characters of, 

 and the phenomena associated with, ground waters, and thereafter to 

 discuss some of the practical points which attach to their use for drink- 

 ing purposes. 



I. — THE SOURCE OF GROUND WATER. 



We are aware that precipitation on land and sea of the moisture of 

 the clouds is the method by which the water borne into the air by 

 evaporation is returned to the earth. The yearly amount of rain which 

 falls in Ontario is commonly more than 30 inches ; but the amount of 

 this that becomes ground water, that is sub-soil or subterranean water, is, 

 owing to its rapid flow from the soil where it falls to the water-courses 

 and to evaporation, probably somewhat less than half of the amount. 

 That this amount which reaches the creeks and rivers is not wholly lost, 

 but to some degree becomes a source of supply to subterranean waters, 

 we shall, I trust, later on produce facts to show. 



To refer to the ground waters of Ontario more particularly, let us 

 recall the geological character of the strata in which these v/aters are 

 found. The Laurentian band of gneissoid rock runs in a north-westerly 

 direction, with its western edge in the neighborhood of Kingston, thence 

 running to the south of Muskoka Lake, thereafter going to form with 

 the Huronian series the islands of the Georgian Bay. Upon this, and 



