652 WATER POWERS OX MERSEY RIVER, X. 8. YORSTOX. 



ment with the ohjeot of measuring and tabnlating the quantity 

 of flow? of all the principal streams of the country. This 

 engineering department, which is called the Hydrography 

 Division of the Geological Survey, embraces amonp- its mem- 

 bers ma'ny of the best well known and foremost men in the 

 profession. They have already accomplished very much, and 

 the statistics gathered as to the flow of streams, the evaporation 

 from water surfaces, etc., are found to be invaluable. Data 

 such as are collected by this corps of men are of great value, 

 as the researches cover a period of time long enough to 

 determine beyond doubt that the results given are correct in 

 every detail, and that they can be absolutely relied on. 



In making an estimate of a water-power it is essential that 

 accurate information be had on the following points : — 



(1) , The flow of the stream, both maximum and mini- 

 mum. 

 (2). The total fall at the power site selected. 

 (3), The practicability of providing storage. 

 (4), A record of the periods of drought. 



The flow of the stream is the one thing most apt to be over- 

 estimated, for with a knowledge of a stream covering only a 

 short period of time it seems to be a most natural thing to for- 

 get that the minimum or dry summer flow is only a fraction of 

 the average flow of the stream, and consequently if a mistake 

 is made in designing or construction of a water-power it is 

 generally an over-estimate of the power to be derived from the 

 plant installed. Up to the present time no such data regarding 

 stream flow of any kind for Canadian streams have been col- 

 lected, but I lun-e 'no doubt but that in the near future the 

 rapid development of the country will lead the government 

 to undertake a work which would lead so directly to the 

 further employment of capital and tend to increased prosperity. 



Of NoYSi Scotia rivers the Mersey is probably the largest, 

 and it is certainly the one best adapted for the development of 



