1854.] 



TORONTO HARBOUR— ITS FORMATION AND PRESERVATION. 



225 



dulatory, lateral, progressive, and retrograde; but, from their 

 assumed equality and the equal times of their application, there 

 could be no resultant. The mean velocity of the wind may 

 properly enough be taken as equal throughout the year from all 

 points of the compass, since the actual difference, as obtained by 

 observations, will effect the results inappreciably ; but the mean 

 force of the waves will not in consequence be equal, as this is 

 greatly influenced by the locality. It is found that the mechani- 

 cal force of a wave depends chiefly on the strength of the wind 

 and the extent of open water traversed; allowing then that the 

 wind blows equally from all points, it will follow that the resultant 

 of the aggregate forces of the waves impinging at any particular 

 place, will be a line lying in a direction opposite to the largest 

 area of open water. 



In applying this conclusion to the beach in front of Toronto 

 we find that the greatest extent of Lake Ontario passed over by 

 winds blowing from any point westward of the perpendicular 

 A B, Fig. 5, does not exceed forty miles, nor is the area of water- 

 over twelve hundred square miles, while to the East of A the 



Fig. 5. 



Fie. 0. 



/ 



waves have a fetch of as much as a hundred and eighty miles 

 over an expanse of water measuring nearly nine thousand square 

 miles; hence then (the duration of the action being taken as 

 equal in both cases) the intensity of the collective forces of waves 

 impinging at A from the eastward is many times greater than 

 that of those from the westward, and the motion of the breach 

 at A must therefore be westerly; it must of course move with a 

 variable velocity because the forces are not constant ; its path, 

 or rather the path of each particle, undulatory, since the forces 

 act impulsively on the plane of the beach in combination with 

 gi'avitation ; it must sometimes retrograde since the direction of 

 the forces is ever changing, and they never act simultaneously; 

 but aggregately, the beach sand, subject to many complicated 

 motions, and acted on by innumeTable and incalculable forces, 

 must move absolutely from east to west, and (taking the forces 

 on each side of line A B respectively as positive and negative) 

 with a velocity proportionate to their algebraic sum. 



On that portion of the beach successively washed by the waves 

 only, can the progressive motion be proved occularly, yet doubtless 

 a similar action must be produced between the breakers and the 

 main land all along the shore, and when we consider that the 

 lake is seldom or never entirely at rest, that even during perfect 

 calms, unless continued for several days, a gentle ripple capable 

 of moving sand is found on the shore, throughout the whole year, 

 therefore, must the materials composing the beach be continually 

 changing place, and although sometimes moving easterly, yet 

 generally, as proved above, in the contrary direction, 



3 



The accompanying drawings of natural groynes very strongly 

 confirm the conclusion here come to. They are copied from 

 sketches recently taken (1850) on the spot, between Privat's 

 Hotel and the Scarboro' Heights. Fig. 6 was formed by the 

 falling of a tree opposite a fisherman's hut east of the Narrows 

 on a passing log : the outer end of the tree was supported by 

 its branches : about one half of the log was floating, but kept 

 stationary by the tree ; the remaining half rested on -the surface, 

 and enabled the sand to accumulate at its easterly side. Figs. 

 1 and 8 appear also to have been formed in a similar manner. 

 They were found on that part of the shore between Ashbridge's 

 Bay and the Searboro' Heights. The dotted lines indicate what 



Fig. 7 



Sketches of natural Groynes. 



-was supposed to be the original water-mark. In all cases, the 

 water was from one to two feet deep on the westerly side of the 

 logs, and in several instances the sand was five or six inches 

 above their upper surface on the easterly side. These groynes, 

 formed by accident, show very clearly the results of the west- 

 ward motion of the beach, and, although simple in the extreme, 

 are natural models from which may be designed other contri- 

 vances for the retention of the moving sand, and will be referred 

 to hereafter in treating of the preservation of the Harbour. 



In addition to these indications of the westward motion of the 

 beach, it may be observed that, on an examination of the mouth 



