REPORTS ON TORONTO HARBOUR. 



The above remarks refer to the first effect ; for the flow of water 

 into the Bay through the western entrance the reaction has also 

 to be considered, and according to the laws of motion, which are 

 applicable to fluids as well as solids, the action and reaction are 

 equal; the action is constant in its effects when the water in 

 the Harbour is raised to the same levels as the water in the Lake 

 a reaction takes place and two currents are established one into 

 and the other out of the Harbour ; and those currents are much 

 increased by the surf on the bar, which acting as a sunken break- 

 water, the surface water is forced into the Harbour by its momentum 

 and returns by the deep channel near the wharf. To the effect of 

 this current may be attributed the steep edge on the inside of the 

 bar, and it has also been found efficacious in scouring the channel . 



The effect produced by an easterly gale is the same, with the 

 exception that as the waves do not break with such great violence 

 on the bar, the additional effect from this cause is lost. 



The difference of level caused by an easterly gale is greater than 

 that produced by a westerly one, as it acts on a larger surface of 

 water. 



As an easterly gale increases the deposit on the bar on the Lake 

 side more than a westerly one, it is evident that a westerly gale is 

 more beneficial in its effects on the maintenance of the channel. 



From the above remarks the conclusion may fairly be drawn 

 that a channel which has been maintained by natural causes fur 

 years past may be injured by an interference with those causes 

 which the construction of a pier on the point of the bar parallel to 

 the Queen's Wharf would most decidedly produce. 



The recapitulation of the several recommendations for the pre- 

 servation of the Harbour will therefore be as follows : — 



1st. The closing of the Don, and diverting the current into 

 Ashbridge's Bay. 



2nd. The sewage of the City to be prevented from being emptied 

 into the Harbour. 



3rd". The strengthening of the Narrows of the Peninsula. 



4th. The continued extension of the Queen's Wharf, so as to be 

 always on a line with the point of the bar. 



That the Harbour can be preserved for ages by the course above 

 recommended I have not the least doubt, and should such a con- 

 tingency ever arise as the removal of the deposit on the base of 

 the Peninsula by any future action of the waters of the Lake, 

 which is extremely doubtful, the recent examinations by boring 

 prove that the substratum is sufficient to bear a stone facing on 

 the Lake side, similar to the one constructed in front of the New 

 Garrison, which has stood the test of six years' experience without 

 any injurious effect, and to resist the action of the waters of the 

 Lake for an indefinite period, so that as far as the decay of the 

 Peninsula is concerned it is altogether mythical, and reduces the 

 question to one of expense. 



THE IMPROVEMENT OF THE HARBOUR. 



With respect to the improvement of the Harbour it is intended 

 to treat this question altogether as a separate matter. 



The only alterations from the preceding remarks on the Preser- 

 vation of the Harbour would be instead of strengthening the Pe- 

 ninsula at the Narrows the opening is recommended. 



The disposition of the River Don, the sewage of the City, and 



the maintenance of the western channel would remain the same ; 

 the question, thetefore, to be considered will be, the practicability of 

 constructing an eastern entrance, its maintenance, and the effect pro- 

 duced on the western entrance in consequence of its construction. 



The engineering difficulties to be encountered in the construction 

 of an eastern entrance will be considerable and attended with 

 much greater expense than at first would be imagined. 



The base of the Peninsula having been ascertained to be of blue 

 clay or hard pan, as it is commonly called, and being five feet 

 from the present surface of the water at this point, the difficulties 

 are rather increased than diminished, though the work when com- 

 pleted would be more substantial than if it was altogether sand. 



The only way in which the blue clay or hard pan can be exca- 

 vated to a depth, so as to afford 12 feet at low water, would be by 

 the construction of coffer dams instead of dredging, which could 

 be resorted to if sand and gravel alone had to be excavated. 



The foundation of the piers would, however, be more secure and 

 less liable to injury from the effects of the heavy sea that will have 

 to be encountered than if sand and gravel formed the foundation. 



Accompanying this Report is a map copied from one in the 

 possession of the City Council which explains the position and ca- 

 pacity of the proposed eastern entrance. 



In order to prevent the "debris" from the Scarborough Heights 

 from being conveyed into the Harbour by the current which will 

 be caused by an easterly gale, it would be necessary to run the 

 piers into 20 feet of water at least, or to the line where the waves 

 break, which indicates the state of the undercurrent; to carry this 

 out successfully will require the piers on either side to average 

 3000 feet each ; the eastern pier to project 500 feet farther than 

 the other, so as to afford sufficient shelter to vessels during mode- 

 rate gales in running into the Harbour. 



For reasons that will hereafter be evident it would not be ad- 

 visable to make the entrance wider than 200 feet. 



The piers would require at least to be 40 feet wide, and loaded 

 with stone in the same manner as the extension now in course of 

 construction at the Queen's Wharf. 



By constructing the piers as proposed it is considered they will 

 be sufficiently strong to resist the effect of the most severe easterly 

 storms, and the piers being run out into 20 feet of water, beyond 

 the extent of the under current, no substance further than the 

 lighter particles of argillaceous matter, which are held in suspension 

 by the agitated water, can enter the Harbour ; and in case of a cur- 

 rent being established through the Harbour, which would occur 

 in an easterly storm, this suspended matter would not be deposited 

 in the Harbour, but would be carried with the current through 

 the western channel into the Lake again, and vice versa in case of 

 westerly gales, in fact it would not be more injurious than at the 

 present time. 



If this is correct the maintenance of the eastern channel cannot 

 be questioned, the effect that would be produced on the western 

 channel requires more serious consideration from the fact, that the 

 back current at the western channel would be lessened in the 

 exact proportion as -the current through the eastern, and this re- 

 mark applies whether an easterly or westerly gale prevails. 

 The data to decide the questions are as follows: — 

 The sectional area of the western channel, including 

 the water on the bar, is in superficial feet 21,350 



