As to (a) strong exception must be taken to the statement that the levelling was not “sufficiently prolonged or extensive.” The levelling operations between Lester Point and “The Backway” were carried out with the same type of instrument and the same degree of precision as the precise levelling along the St. Lawrence and elsewhere in Canada.
As to (b), the argument lacks clarity but it seems to be, in essence, a statement that, if access to the waterway under consideration is obtained through “a short, deep connecting waterway” which then expands into a lake, said lake and short, deep connecting waterway form an Inlet but, if access is had from “an undoubted inlet of the sea” into the St. Lawrence “river system,” a “choice of criteria must be adopted.”
Unfortunately, no “choice of criteria” is set forth and we are left in the dark, both as to Admiral Learmonth's dictum respecting the position of the mouth of the St. Lawrence and of the other criteria which would enable us to decide the upper and lower limits of choice.
Just why the “short, deep, narrow connecting waterway” exercises such an overwhelming influence in the determination of the riverine or nonriverine status of the lower Hamilton is not clear.
As to (c), it is stated that :
“Lake Melville is nevertheless an Arm of the Sea, although owing to its expanse, depth of penetration into the interior of the country, and general configuration it possesses the characteristics of a Sea Inlet in a less degree than the Sound seaward of the narrows.”
Like the “short, deep, narrow connecting waterway,” the “expanse,” “depth of penetration into the interior” and the “configuration” of Lake Melville have no bearing upon the question so long as there is a fall at its outlet and such fall has been demonstrated.
X. Admiral Learmonth states that, if the amplitude of the Tidal wave were very much less than it is (6½ feet maximum), conditions in lake Melville “would then be similar in some respects to those prevailing in the Dardanelles and the Sea of Marmora.”
Inasmuch as there is a definitely ascertained fall in the “narrows,” there can be no doubt that a decreased range of tide would result in lower salinity than at present.
Further, comparisons of conditions in the Sea of Marmora which is demonstrably at the same level and practically of the same salinity as the Mediterranean are hardly pertinent.
XII. Admiral Learmonth states that :
“The distribution of Fresh Water on the surface, due to the drainage of rain water and melted ice and snow, may have been abnormally large in the 1923 season.”
This supposition has already been dealt with. It has been pointed out that there is no evidence that 1923 was an abnormal season and that it would be just as reasonable to say that the “distribution of Fresh Water on the surface” may have been abnormally small.
XIII. Admiral Learmonth states that the suggestion in the Canadian Case that " the connecting Waterway between lake Melville and the Sound extends seaward as far as Turner and Ticorolak headlands, 10 miles from the entrance to the Narrows, is in my opinion entirely incorrect."
As the officer in command of the Acadia during the survey of lake Melville in 1921, I am of the opinion that it may be fairly contended that the mouth of the Hamilton river is defined by a line drawn from Ticorolak to Turner headland, but, in any event, it cannot be successfully contended that it does not extend, at least, to that point.
As to the contention that there are :
“Sufficient reasons of Imperial Policy against placing Lake Melville in the category of River Systems, instead of, as heretofore among the Sea Inlets, inasmuch as a new precedent would be thus set up which would involve a general re-classification of similar Water-Basins joined to the sea and an alteration in the standards now applied to determine their nature, and further any such change might very likely serve to prejudice the position of the British Empire, as a maritime power, in any future Territorial disputes or Congresses with other Nations.”
I cannot acquiesce in this statement, for I fail entirely to understand how, if Lake Melville is placed in the category of a river, a new precedent for determining the territoriality of a similar waterway would be set up or the position of the British Empire as a maritime power prejudiced. Whether lake Melville is a part of a river or an inland sea, it is by English law a part of the Dominions of the Crown. It is inter fauces terroe, and, there-fore, part of the British possessions in America. Also, it seems to me that Admiral Learmonth's argument is based on a false assumption, for lake Melville has not, heretofore, been placed among sea inlets, if by that term he means it has the character of an inland sea. The history of this expanse of water shows that it has always been considered as riverine rather than marine in its characteristics. The French, as early as 1704, recognised its riverine quality. Commander William Martin, H.M. Brig Clinker, took the same view : for, in his log for July 1821, he states that he sailed up the “River Ivucktoke,” meaning lake Melville and the waterway which discharges it, and I surmise that it was in view of the information communicated to him by this officer that A. Arrowsmith, Hydrographer to His Majesty, when he published his chart in June, 1825, incorporating in it a survey of this waterway, determined to classify it and name it as a lake—a lake-expansion of the river. That these early views as to the characteristics of this water-way are correct is amply borne out by the levelling and tidal operations carried out under the directions of the Government of Canada in 1921 and 1923.
ANNEX “A” TO No. 1447.
SUPPLEMENTARY REPORT ON PRECISE LEVELLING IN LABRADOR.
BY R. H. MONTGOMERY,
Chief of Levelling Division, Geodetic Survey of Canada.
After perusal of Vice-Admiral Learmonth's report I find the only reference to the precise levelling operations is contained in the following extract of Paragraph VI :
“Although the time available was short, and it was not possible to employ the test of a closure for the actual levelling observations between the two Tidal stations, the following conclusions as to the determination of the Tide Level Slope between the two Stations mentioned may be accepted as substantially accurate during the period embraced.
(a) That at any instant throughout the period of the observations there was a Definite Slope of the water surface between the two Stations, the Mean Tide Level of the Lake Melville Station being higher than that of the Lester Point Station.
(b) That the Average Difference between the Mean Tide Levels of the two Stations during this period was 5 inches.
(c) That the difference was not always constant, but subject to variations at the times of Spring and Neap tides, being greater during the outgoing than the incoming tide, and greatest during the Neap tides.”
In other words, Admiral Learmonth accepts as substantially accurate that during the period embraced, the Mean Tide Level at the Lake Melville station was, on the average, five inches higher than Mean Tide Level at the Lester Point Station.
In view of the frank acceptance of this fact, which was the result ascertained by the tide gauge records and the levelling operations, further
comments on this phase of the case would appear unnecessary. However, while I am satisfied that Admiral Learmonth, in view of his undoubted technical ability, had no intention, inferentially or otherwise, of casting any reflection on the accuracy of the levelling operations, I believe his remark “Although the time available was short, and it was not possible to employ the test of a closure for the actual levelling observations between the two Tidal Stations.” may tend to create such an impression. To obviate this, I feel constrained to elucidate my original report on the levelling operations as contained in the Canadian Case in reference to this particular remark.
When the Geodetic Survey of Canada was requested to carry out this investigation, in view of the undoubted difficulties of running precise levels in such a country and the probable importance which the results might have, it was decided that I should personally take charge of these operations. Special care was taken throughout the execution of this work, and, in my opinion, the precise levels under consideration, as far as precision goes, compare favourably with any of the 22,000 miles of precise levels which have been run in this Dominion under the supervision of the Geodetic Survey of Canada.
In spite of the precision and refinement now exercised in precise levelling, there still remain inherent errors of a small order, resulting from accidental and systematic causes. In developing a national system of levels it is customary to run the lines in such a manner as will form a network of polygons, or circuits. In this net, each circuit closure represents the algebraic sum of these small errors in its perimeter and, by a rigorous mathematical adjustment of the net in its entirety, these closures are reduced to zero. While the adjustment removes the small inherent errors, its effect on actual difference of elevation between two adjacent bench-marks is so slight as to be undeterminable by field operations. Hence, in an isolated short line of levels, as occurs in the Labrador work, where a difference of elevation of the magnitude of 5 inches was under consideration, it was manifestly out of the question to secure a circuit closure even if the country had permitted doing so.
It is true that, while a circuit closure also reveals the presence of a gross error that is one which would be detected by field operations. In our precise levelling procedure, the route to be levelled is divided into sections, approximately one mile in length and, on each section, at least two lines, one forward and one backward, are run under as different atmospheric conditions as possible. If the difference of elevation between the terminal bench marks of each section, as determined by these two lines, is more than 0.015 of a foot, then additional lines are run until this agreement is reached. These additional lines are designated as relevelling. Owing to the exceptionally difficult nature of the route, the amount of relevelling on this line was unusually high. At times, as many as six separate lines were run in a section before this agreement was reached. Consequently the possibility of a gross error existing in this work is negligible.
The formula for determining the probable error of a line of double levelling is
probable error = 0.67 d2
where d = the local discrepancy in feet between the forward and backward measure in such section
m = length of each section in miles
n = number of sections
L = length of the line in miles.
The probable error of this line, using the above formula, is ±0.012 feet or ±0.14 inch, which is well within the limits adopted by the International Union of Geodesy and Geophysics as their standard for levelling of high precision.
R. H. MONTGOMERY.