39 



crust, and in studying the results oi formation and deposition, we must not ignore 

 or forget tlie equally potent agencies of denudation and destruction without which 

 latter the f.-rmcr could have no existence. These marvellous changes which the 

 solid crust of our planet has undergone are graphically described in Tennyson's 

 lines : 



" There rolls the deep where grew the tree ; 

 Earth, what changrns hast thou seen! 

 There, where the long street roars, hath been 

 The silence of the central sea. 



The hills are shadows, and they flow 

 From form to form, and nothing stands, 

 They melt like mist, the solid lands 

 Like clouds they shape themselves and go." 



The Secretary i^ead a coiuraunication from Mr. H. M. Ami, 

 entitled : " Notes on an exposure of the Potsdam Formation at Bucking- 

 ham Basin, Lievre River, Quebec," of which the following is a brief 

 abstract : 



After referring to the paucity of exposures of the Potsdam in this neigh" 

 bourhood the paper described an outcrop occurring about one mile from the 

 mouth of the Lievre River, and consisting of a series of strata with a S. E. dip 

 and a N. E. and IS. W. strike, the angle of the dip being about 15°. The rock is 

 a finely grained, or coarse sandstone or quartzite ; many of the strata containing 

 small rounded pebbles of quartz, especially abundant at the divisional planes. 

 Some of the strata are cf considerable thickness and may be valuable as building 

 stone ; the remainder are thin and disintegrate rapidly. They vary in colour from 

 white to chocolate and blood-red. The total thickness of the section is estimated 

 at about 44 feet, but of this only about 29 feet are visible, the remainder being 

 below the water line. The series rests upon a bed of very coarse quartzite con- 

 glomerate, constituted of large smooth pebbles embedded in a matrix of detritus 

 from the adjoining Laurentian rocks. There is little or no evidence of the 

 presence of organic remains in these strata, except small cavities on the surface 

 planes which are supposed to have sheltered sponge-like organisms. Even 

 seolithes, so common in the Potsdam, was not found here. The surface of the 

 exposure shows strife, resembling those made by glaciers, having a S. by W. or 

 S. S. W. direction, and ripple marks also occur in some places. 



THIRD SOIREE. 



Friday, January 13, 1882. — Filterings from the Water Supply of the City 

 OF Ottawa. Eev. A. F. Kemp, LL.D. 



The water supply of cities and towns has everywhere become of the 

 p-eatest importance to the public health. Water is not only a necessity of life, 

 in its pure and simple state, but it may become the subtle medium of disease 

 and death. It is a chemical solvent of many pernicious things, and even when 

 most translucent may contain innumerable microscopic forms and germs of plants 

 and animals that may become the virus of the most fatal diseases. It is well 

 known that zymotic diseases are due in a great measure to the impurities in 

 watei-, and that they become epidemic through water more than in any other 



