[2 



REPORTS ON TORONTO HARBOUR. 



not, it may be" very reasonably supposed, represent one-fourth 

 part of the mass of water projected into Ashbridge's Bay over the 

 low beach, during the long continued easterly storms which dis- 

 tinguished the month of April. It is therefore urged, that any 

 attempt to pronounce an opinion upon the effect produced upon 

 the entrance to the Harbour by the late opening near Privat's 

 Hotel, must be entirely theoretical, as it cannot be fairly repre- 

 sented by soundings taken in April of the present year. It is im- 

 portant, to ascertain, how this mass of water projected into Toronto 

 Harbour by the Don and through the breach at Ashbridge's Bay, 

 distributed itself in passing out of the Harbour entrance. The tem- 

 perature of the water determines the solution of this problem. Six 

 or eight trials showed the temperature of the water to vary from 

 38 to 42 degrees, both in Ashbridge's Bay, the Lake, and the 

 Harbour. This is within two degrees both above and below the 

 temperature of water at its greatest density, (39° 6,) consequently, 

 the density of the water may bo regarded as uniform, and hence, 

 the current would be equally distributed over the bar at the 

 entrance to the Harbour, modified by a current produced by the 

 easterly gales, noticed hereafter. In summer, it is probable that 

 the surplus water would have escaped, almost entirely, over the 

 bar at the mouth of the Harbour, and would have had little effect 

 upon the channel in deep water. The effect of temperature is 

 beautifully shown in the currents which are established during 

 the summer months at the Harbour entrance, and requires a 

 detailed notice. The most permanent current in the Bay, having 

 an outward direction, is, of course, due to the Don ; but the 

 waters of the Bay and Don, being shallow, rapidly acquire an 

 elevation of temperature, by exposure to the sun's rays ; their 

 specific gravity is therefore diminished. The deep waters of 

 the lake do not attain the same elevation of temperature, and are, 

 consequently, heavier than the surface waters of the Bay. The 

 warm and light waters of the Bay are pushed out over the bar by 

 the colder and heavier waters of the Lake, irrespective of the cur- 

 rent of the Don. The cold Lake water enters at the deepest 

 part of the mouth of the Harbour, and during the summer months 

 establishes an inward current, often remarked. Two other cur- 

 rents of importance are to be noticed; — 1st. An under, outward 

 current, which is occasioned by westerly winds impelling the 

 waves of the Lake over the bar into the Bay : the same influence, 

 however, pressing upon the waters of the Lake, raises them at its 

 eastern extremity and lowers them at its head. In order to es- 

 tablish equilibrium between the level of the waters in the Harbour 

 and those in the Lake, an outward undercurrent is established, 

 which, in prolonged westerly gales, is very marked. 2nd. An 

 inward under current at the mouth, when easterly winds are 

 blowing, which have the effect of driving the waters out of the 

 Bay, and at the same time, raising the level of the water at 

 the head of the Lake ; in order to preserve equilibrium, a power- 

 ful under inward current is established in the deepest water at 

 the mouth of the Harbour. 



It is evident that these currents have given to the sand-bar now 

 threatening the mouth of the Harbour its peculiar conformation, 

 as shown in Mr. Fleming's chart. These currents cease to exist 

 during the maintenance of an opening, either in Ashbridge's Bay, 

 or at the east end of the Harbour. Their conservative influence 

 in retarding the progress of the shoal northwards, and its inva- 

 sion of the entrance of the Harbour, cannot fail to be noticed : 

 they form another objection against the construction of permanent 



.openings in the localities named. The late Mr. Boy, C.E., who, as 

 before stated, paid much attention to the phenomena of the Har- 

 bour, well describes the influence of these currents in his paper 

 published in the Monthly Review, for June 1841. 



It is sufficiently clear that the currents just described, irregular 

 and accidental as they are, and deriving their very existence from 

 the conformation and growth of the Harbour, can only be sup- 

 posed to exercise an influence, (and moderate in its effects,) upon 

 the form of the sand-bar which threatens the mouth of the 

 Harbour. 



An effect requires a cause : the cause of the currents is the pre- 

 sence and form of the peninsula, without which they would not have 

 existed ; the currents are destroyed by destroying the integrity of 

 the peninsula. It -follows, as a matter of course, that the currents 

 could not have produced that which has given birth to them ; an 

 hypothesis which, in spite of the contradictions it involves has yet 

 found supporters. 



The writer presumes that the Harbour Commissioners .will 

 permit such an interpretation of their words, " Means to be 

 adopted for the improvement and preservation of the Harbour," 

 as to allow the introduction into this Report of remedial measures 

 which have not been specially referred to in their published 

 notice. 



The suggestions which the writer begs leave to submit are in- 

 troduced, without present comment, into the following recapitula- 

 tion of the statements advanced in relation to the history, forma- 

 tion, and preservation of the Harbour. 



1. The Harbour, in its utmost extension, is altogether a modern 

 formation. . 



2. Its formation is due to the present existing protecting head- 

 land of the west commencement of Scarboro' Heights. 



3. Its original form was a sand-bar, or shoal, deposited under 

 the protecting headland, in a position a little to the south of its 

 present situation. The materials of which the sand shoal was 

 composed were derived from the east, being impelled by easterly 

 winds during a period - of high water, and then washed up into a 

 beach during a period of low water. 



4. The Don exerted no influence whatever on the original for- 

 mation or extension of the sand beach, but the beach was extended 

 westerly, under the headland, by the same causes which originated 

 it, until it advanced so far as to be removed from the influence of 

 the protecting headland. Subsequently, it was swept round in a 

 northerly direction, more particularly by south and west winds, 

 until it enclosed the space now occupied by the marshes of the 

 Don and Ashbridge's Bay. 



5. The whole valley of the Don was excavated ages before the 

 enclosure took place, and the marshes have been produced by the 

 same vegetable growth which now converts the ponds of the penin- 

 sula into reedy swamps. (Witness the ponds south of the Light- 

 house, during the present generation). The detritus of the Don 

 has accelerated the formation of its marshes, but that detritus 

 consists only of the fine mud which can be mechanically suspended 

 in water. 



6. The peninsula proper has been formed by "travelling beaches," 

 impelled along the boundary of the present Ashbridge's Bay and 

 its westerly extension. There is every probability for supposing 

 that each successive beach, as shown by the dotted lines on Chart 

 6, and Sketch 10, are permanent records of Low Lake Levels. 



