Paper No. 34.

THE CORNWALL CANAL.

BY S. KEEFER, M. CAN.SOC.C.E.

Of the first construction of the Cornwall Canal, during the years 1834 to 1839, it is proposed in this paper to present to the Society such an account, from personal knowledge, as an assistant engineer, resident on the works during those years, is qualified to give. Reference to the enlargement thereof, now in progress, will also be made as an engineering question.

The Cornwall Canal was the first of the series of canals on the St. Lawrence, constructed for the larger scale of steamboat navigation. In 1832 the Legislature of Upper Canada appropriated the sum of $280,000 for the improvement of the navigation of the St. Lawrence, to admit the passage of vessels drawing nine feet of water, and recommending the immediate commencement of the improvement between Cornwall and the Long Sault Rapids, stipulating for the completion of the Cornwall Canal before any other works leading to Lake Ontario should be undertaken. A commission was appointed in 1833 to carry out the provisions of the act, and by them the surveys and plans for the works were entrusted to experienced engineers from the United States.

The preliminary survey was conducted by Mr. John B. Mills as chief engineer, with Mr. Benjamin Wright, or Judge Wright, chief engineer of the Erie Canal, as consulting engineer. Mr. Mills brought with him three assistants, and the writer made the fourth. Mr. William J. McAlpine took the levels. The writer made the survey, and Mr. James Worrall and Mr. Charles Mills were the draughtsmen. The field work was soon accomplished. It was begun the 13th May, 1833, and completed 2nd July of the same year. The engineers then proceeded, under the same authority, with the survey of the St. Lawrence thence to Lake Ontario, and submitted plans and estimates for the canals proposed to be constructed at the Long Sault, Farran's Point, Rapid Plat, Point Cardinal, and the Galops, amounting in all to $1,294,464. In September and October of the same year, the writer assisted Mr. Mills in the survey for a canal in continuation of the Cornwall Canal, and of the same dimensions, in Lower Canada to

connect Lake St. Francis with Lake St. Louis, and to overcome the rapids at Coteau, Cedars and Cascades. This survey was confined to the North Shore, and referred to two routes, one along the river bank at these rapids and the other inland.

The following year, 1834, the final location of the canal was begun at Dickinson's Landing, at the head of the Long Sault Rapids, on the 20th May. On the 30th of the same month the Canal Commissioners, of whom Mr. Jonas Jones of Brockville was president, came down to examine the plans and proposed line of canal. They were accompanied by Captain Cole of the Royal Engineers, by their chief engineer, Mr. J. B. Mills, by Judge Wright, the consulting engineer, and by Judge Geddes, another engineer from the Erie and Champlain Canals. As the two American engineers, Judge Wright and Judge Geddes, had borne conspicuous and responsible parts in the construction of the Erie Canal, it was considered that their knowledge of canal works would be valuable to the Commissioners. Captain Cole and Judge Geddes had been specially retained to advise the Board in reference to the selection of the best line for the canal. Mr. Mills had served under Mr. Moncure Robinson, an accomplished and distinguished engineer of Virginia, and came to his work in Canada well informed, and with perfect confidence in his own ability. He was a man of great determination, and having once made up his mind as to his plans, and the course he intended to pursue, he was immovable.

As the result of this examination by the Commissioners, and the engineers both civil and military who attended them, the chief engineer's plan was approved, and the works were placed under contract the same year. It may here be stated that with the exception of a few changes. of the centre line at the Long Sault, to throw the canal more inland, the location of the canal as now constructed is the same as that origi. nally projected by Mr. Mills, and adopted by the Commissioners.

The engineers determined on locks 55 feet wide 200 feet long between the gates, and with nine feet of water on the sills. These dimensions would allow the passage of vessels 175 to 185 feet long, according to their build. The canal was to be 100 feet wide at bottom and 150 feet at surface to admit of the side paddle steamboats then in use passing each other in any part of the canal. The great capabilities of the screw as a means of propelling vessels had not at that time been developed, and propellers were not then employed in our inland navigation. This accounts for the very generous width given to the canal.

The length of the canal is 11 miles. There is one guard lock at the head, and there are six lift locks of 8 feet lift each, to overcome the

whole fall in the river of 48 feet, from the head of the Long Sault to Cornwall bay at the head of Lake St. Francis. This scale for the navigation of the St. Lawrence was approved by the Commissioners and adopted by the Government, and became the standard for the other short canals above Cornwall, except that as vessels could there descend the rapids outside these canals with safety, the bottom width was reduced to 50 feet. The width of the locks on the Cornwall Canal 55 feet, as fixed by the American engineers, was not in reality available for vessels of that width, owing to the peculiar form of the lockwalls, and therefore, when the Williamsburgh canals (the name given to the short canals at Farran's Point, Rapid Plat, and the Galops) were afterwards constructed, as well as Beauharnois and Lachine canals, the width was reduced to 45 feet, which was considered in better proportion to the length and draught.

An account of these locks as built, with plans of locks, lock gates and the machinery for operating them, was published with the report of Colonel Philpotts, R. E., on the proposed enlargement on the Welland Canal in 1840, and need not be repeated here. This report was made under instructions from the Earl of Durham, and was addressed to the Right Honorable Sir Charles Poulett Thompson, Governor General, and published in the "Professional Papers of the Royal Engineers," Vol. V, pp. 140 to 193.

THE LOCATION.

In taking his departure from the navigable waters of the St. Lawrence above the Long Sault, the choice of two lines was presented to the engineer. One was to follow along the river bank down to the channel dividing Sheek's Island from the main shore, and the other an inland route up Hoople's Creek, and by a depression half a mile back of the river to meet the same channel at Sand Bridge on Brownell's Bay. The first was along a high bluff bank rising 30 to 50 feet above the river, all side cutting, and the other a through cut.

The engineer having instituted a comparison between these two lines decided in favour of the one by the river, as being a mile and a quarter shorter, and saving $120,000 in cost. An engineer's assistant may not question the superior judgment of his chief, but loyally accept his decision, seeing he is in no way responsible.

The correctness of this estimate has recently been called in question, but whether right or wrong, no good end can be served by the discussion of it now, for the very good reason that the officially adopted line

has been constructed, and in use for half a century without accident or failure of any kind. The subject is now a dead issue.

It may be observed, however, that the front or river line being all in side-cutting with short delivery into the river, a cubic yard of material could be moved at less cost than in a through cut inland, where it has first to be elevated, and then carried some distance into spoil bank. Probably two yards could be moved on the front line at the same cost as one yard on the inland route, or double the quantity for the same

cost.

THE SUMMIT LEVEL.

There can be no doubt that the engineer was perfectly right in maintaining his summit level, and carrying it on as far as he could, so as to command the table-land eastward of Milleroches, to his first lift lock, but his location of the canal along the three miles of circuitous side cutting, from the Long Sault to Milleroches, cannot be approved, when there was, as will appear from what follows, no necessity for resorting to such a hazardous location, but in view thereof, a safe and less costly means of keeping up the summit level. The maintenance of the summit level was correct in principle, because when the line had reached Milleroches, the engineer was independent of the river, and thence to Cornwall could locate his locks to the best advantage. On the other hand, many of the contemporary engineers, both civil and military, who had other plans to suggest seemed to have lost sight of this essential principle. They proposed to lock down into the Sheek's Island channel, and to render it navigable by dams at Moulinette and Milleroches, or simply by one dam at the latter place made high enough to drown out the rapids at the former. It appears this was suggested in order to avoid the great cost and risk of hanging up the canal in side cutting on the north shore; but by this proposed drop to a lower level they had to encounter a deeper cutting of some seventeen feet or more eastward of Milleroches till the first lift lock was reached. They all suggested that a low dam, to serve merely as a coffer-dam, should be thrown across the shallow channel, called the " Snye" at the head of Sheek's Island, to shut off the water coming down that channel during the construction of the proposed works at Moulinette and Milleroches, or possibly to serve, if maintained, as a regulating bulk head for the supply of the canal after it had been built. Mr. Peter Fleming, Mr. Samuel Clowes, Judge Geddes and Captain Cole, R. E., favoured plans of this sort; but Mr. Clowes went beyond the other engineers, and suggested a lock in the dam at Milleroches, and continuing the canal

along the margin of the open St. Lawrence to the head of the Cornwall Rapids, and thence along in front of the town to the bay below Cornwall.

Of all these rival schemes the assistant engineer was at the time entirely ignorant, and in no way concerned with them, being then actively employed in the location survey of the chief engineer's adopted line. But while so engaged, he had naturally become familiar with the physical features and capabilities of the country for canalization, and began to form opinions of his own on the subject. To him it appeared a surprising circumstance, that after all the array of professional skill that had been convened to assist the Commissioners in the selection of the most feasible plan, they should all have overlooked one simple and obvious idea that would have given a satisfactory solution of the main difficulty with which they were all contending-namely, the cost and hazard of carrying the summit level of the canal along the left bank of the river, where the surface of the canal would be from 16 to 24 feet above the surface of the river, and where the suitableness or otherwise of the material for making sound banks was as yet unknown.

The idea that presented itself to the mind of the writer was to have no canal at all on the north bank, but in lieu thereof, to raise the dams at the head and foot of Sheek's Island, high enough to retain the summit level of the canal, and transform the river valley into a fine broad basin, making that the canal. If both dams were raised to the same level, they would obviate the necessity of constructing three miles of canal along the north shore. The foundations for these dams would be secure, for they would be on hard, gravelly earth or solid rock. The width of the channel at the head of the Island is 230 feet, according to the survey presently to be referred to, and at the foot of the Island 330 feet. In both cases the water is quite shallow-the same quantity passing at both places, and the banks are high. Sheek's Island would form the south, and the main land the north bank of the canal, or basin, created by the two dams. The upper dam, if raised five feet above canal surface, would stand 26 feet high in the middle, and the lower dam 40 feet high, allowing in both cases for four feet of water in the rapids, which is believed to be in excess of the actual depth.

The idea of two dams of the same height, both raised to summit level, does not appear to have been grasped by any of the engineers before mentioned, and when the assistant engineer ventured to suggest it to his chief, it was treated with scant courtesy, and at once dismissed, and was never again referred to. Could it be that the chief did not understand what his assistant proposed? It is believed that a survey and