564 Notices of Ifemoirs — The British Association. 



between the inci-eased supply and the discharging power thus 

 tends by retrocession then to equality and to balance. 



9. All the features of Niagara being dependent on the force of the 

 waters, every attempt to diminish this force by what is known as 

 the utilization of the Falls would change these features, and if the 

 utilization were carried to the extent sometimes proposed, these 

 features would be destroyed. Abstract the vis viva from the water, 

 and we have only a mass of inert matter. 



10. And it may be questioned whether even the material argu- 

 ment in favour of utilization, great as it is, is so conclusively in 

 favour of the utilizer as is often supposed. It is admitted that 

 Niagara has played no mean part in the geographical evolution 

 of this part of the continent ; and, it may be noticed, does it not 

 now play an equally important part in its preservation? In the 

 Niagara descent is generated the impulse which commands the cir- 

 culation both of the Upper and Lower Lakes, and hence to some 

 extent the drainage, rainfall, and cultivation of their adjacent areas 

 of country. The Niagara impulse, some four and a half million 

 horse-power, moves the waters down from Erie and drives them 

 through Ontario. If this impulse be wholly or even largely 

 withdrawn in the manner proposed, what may be the effect on 

 the circulation of this continental district ? If this is not now a 

 practical question, the propositions now in the air may soon make 

 it one. 



7. Eesults of Past Experience in Gold Mining in Nova Scotia. 



By Edwin Gilpin, Jun., A.M., F.G.S., F.R.S.C. 

 rpHE gold-fields of Nova Scotia stretch along the whole Atlantic 

 I coast of the province, and occupy an area of about 7000 square 

 miles. 



The auriferous measures may be divided into two series, an upper 

 one consisting of black pyritous slates with occasional beds of 

 qnartzite and some auriferous veins and a lower one made up 

 of alternating beds of slates and quartzites and compact sandstone, 

 sometimes felspathic. The upper series is estimated to be 3000 feet 

 thick, the lower 9000 feet. 



Granite rocks stretch irregularly the whole length of the gold 

 fields. The granite is evidently intrusive, and is older than the 

 Carboniferous period. 



The auriferous veins vary in thickness up to six feet ; the usual 

 size of those worked is only four to fifteen inches. The quartz is 

 often crystalline and banded. The veins have the same strike as the 

 inclosing rocks, and were at first considered to be beds, similar to 

 those known to be auriferous in the Carolinas and elsewhere; but 

 the fact of their containing portions of the inclosing slate, and of 

 occasionally cutting obliquely across the bedding, proves that they 

 are true veins. 



The distribution of the gold in the veins may be termed capricious. 

 While the veins for a long distance may be auriferous, there is 

 generally one zone or several zones of quartz much richer than that 



