OP THE RIVER SAINT LAWRENCE. 



263 



." She makes the downward trip easily enough in ten hours, and the upward in from 

 eleven to twelve hours." 



In 1819, the canal system was hegun in the construction of the Lachine Canal, and 

 following this, other works of the same nature, for the improvement of the Ottawa and 

 the St. Lawrence, which will hereafter be described. 



From Montreal, up the natural course of the river, there is a series of rapids which give 

 a high velocity to the water, in some cases not less than eighteen miles per hour, which 

 give rise to a rapid turbulent stream, over a rocky bottom of an uncertain depth ; alter- 

 nated with lakes or wider stretches of the river, which have reduced the velocity to a 

 minimum of half a mile per hour, in the centre of Lakes St. Louis and St. Francis. 



The portion of these rapids and lakes, as well as the width and depth of the river, can 

 be best described by referring to a map, which is appended to this statement, giving all 

 the leading features for the practical consideration of this subject. And attention is par- 

 ticularly invited to the large general charts of the river from Brockville to the neighbor- 

 hood of Montreal, which afford the best available material for the study of this interesting 

 river. A tabulated statement is also given in the Appendix (marked 7) to this, which 

 gives the slopes of the surfaces ; but it may be remarked generally, that while the maxi- 

 mum slope in the Sault Rapid is on an average seventeen feet per mile, the minimum 

 slope of the fiat part of the river, between Brockville and Prescott, where flowing in a 

 tolerably uniform regime, is one inch per mile for a length of about twelve miles. 



It is to be regretted that circumstances have not encouraged or induced the under- 

 taking of any sufficiently extensive observations upon the discharge of this river, through 

 these or any other localities ; for unless undertaken professionally, it is scarcely to be 

 expected that a zealous devotion to science per se, would venture upon a set of experi- 

 ments which, to insure sufficient accuracy, must be continued over a long period, and 

 especially under circumstances such as those which have been referred to in another part 

 of this paper. 



ST. CLAIR PLATS. 



Among the works undertaken on the line of inland navigation, is the deepening of the 

 St. Clair Flats, forming the delta at the head of the shallow lake elsewhere described. 

 Up to the year 1856, great inconvenience was felt at this point, particularly at low stages 

 of the western waters, where there was barely six feet of water in some places ; and to 

 escape the shoals and shifting sands (which in rough weather were even dangerous), it 

 was the common practice to lighten, at a considerable cost, a part of the cargoes of the 

 ordinary lake schooners. 



The attention of the United States and Canadian legislatures was at length success- 



