Niagara Falls 



1907 to show that the 1 842 map is badly in error as to the American 

 Fall, but probably correct as to the Horseshoe. A perusal of the 

 pamphlet brings out nothing more clearly to the engineer than 

 that the various surveys disagree to a remarkable extent. Equally 

 remarkable is the fact that the 1905 survey, which doubtless 

 was intended to be better than the previous ones, was made with 

 a plane-table, giving no numerical record, but only a map-plot, 

 of the results. This survey is separately reported, in the same 

 bulletin (Bulletin No. 306), by W. Carvel Hall. 



1907 Spencer, Joseph William Winthrop. Falls of Niagara: their 



Spencer evolution and varying relations to the Great Lakes; characteristics of the 



power and the effects of its diversion. (Can. dep't of mines, geol. survey 

 branch. Ottawa: S. E. Dawson. 1907.) 



This monograph on the geology and physics of the Falls of Niagara 

 gives in detail the scientific results of the survey made by Mr. Spencer in 

 1 906, with many references to the conclusions of other geologists regarding 

 Niagara. 



Niagara and its history are so familiar that most people natu- 

 rally conclude that almost everything concerning the Falls has 

 already been made known, so that additional work suggests 

 little more than a re-description or essay writing. Among the 

 various contributions to the literature, only a few, in number, 

 bear upon the geological aspect, and fewer still have made addi- 

 tions to our knowledge of the subject. Yet such contributions, 

 as will be seen from many necessary discoveries announced in 

 this book, formed chapters too incomplete upon which to estab- 

 lish the science of the Falls. This statement applies not only 

 to their geological, but also to their physical, aspect. Thus, 

 while the volume of the river had been measured for power pur- 

 poses, some of the most important problems in its physics had 

 not been elucidated by the engineer — not merely those bearing 

 on the future of the Falls, but even that of the mean discharge 

 given. The recession of the Falls through the different strata 

 is the ordinary limit of research required of the geologist. But 

 the changes, in the volume and currents of the river, in the height 



670 



