88 TKANSACTIONS OF THE [jAN. 31^ 



While it would obviously be undesirable to establish a driven 

 well plant within the limits of a populous city, it may be said 

 that the necessity for so doing is never likely to occur. More- 

 over, the purifying influence of the soil by infiltration is known 

 to be very effective ; the well-known processes of sewage dispo- 

 sal by irrigation and downward filtration are based upon this 

 property of the ordinary porous soils. 



A microscopic analysis of the eflQuent water from the irriga- 

 tion fields of Paris showed that the number of microbes in the 

 sewage was reduced from 20,000 per cubic centimetre to 12 per 

 cubic centimetre, and that the effluent water from the irrigation 

 fields contained fewer microbes than the water supplied to Paris- 

 for domestic uses. (See Gray's report to the City Council of 

 Providence.) 



The water being drawn from considerable depths, usually, the 

 purifying effect of the slow downward filtration from the surface 

 would probably be much more complete than is produced by any 

 artificial filtration. 



It should be a source of public congratulation that, while our 

 rivers and streams must become polluted by a growing population^ 

 nature furnishes another source of water-supply so abundant 

 and widespread, so pure and so easily procurable. 



Explorations and investigations having in view the more- 

 thorough study of this underground water-supply deserve, and 

 should receive at the hands of the public, the most earnest ap- 

 preciation and encouragement. 



Prof. A. A. Breneman spoke as follows : 



Every plan for supplying water for domestic use to cities must 

 be regarded from the standpoint of the chemist as well as from 

 that of the engineer. Unfortunately for sanitary interests, it 

 often happens that the chemist is called in only when some glar- 

 ing defect in the operation of a system is met with which might 

 have been prevented if his counsel had been sought at the be- 

 ginning. Considerations of quantity and permanence of supply, 

 so important in themselves, have too often been allowed to over- 

 shadow the question of the quality of the water to be used. As 

 a result of this policy, we have to face the fact that not one-tenth 



