23.  The results of the operations of this division are embodied in a map and profiles, which are herewith presented.  The degree of reliance to be placed on this map will be best understood from a detail of the methods employed in preparing it.

The river Metis and its branch, the Mistigougeche, were surveyed by an azimuth compass of Smallcaldus construction, and the distances measured by a micrometric telescope by Ertil, of Munich.  The courses of the rest of the lines were determined by compasses of similar construction, and the distances measured by chains of 100 feet constructed by Dollond, of London, and Brown, of New York.  An exception to this general rule exists in the survey of the eastern side of Rimouski.  The courses and distances thus measured, and corrected for the variation of the compass, were compared with astronomic observations for latitude and with longitudes deduced from chronometers.  For this reason, as the line on the east side of Rimouski is almost in the direction of the meridian, it was not considered necessary to lose time in measuring it when the latitude of the several camps, determined by observations of the pole star, were taken nightly.

The latitudes of the courses under the direction of Mr. H.B.  Renwick were determined by a reflecting repeating circle of Dollond; those on Mr. Lally’s by a good sextant.  The latitudes and times at Grand Metis, the river Du Loup, and the stationary camp on Mistigougeche and Abagusquash were principally determined from observations made with the Dollond circle.  Lunar transits were taken at the river Du Loup, and distances of the moon for longitude at several places on the line.  The reliance for the longitudes was, however, principally upon timekeepers, and of these the party was furnished with one box and two pocket chronometers by Parkinson & Trodsham, one pocket chronometer by Molyneux, one by French, one by Barraud, and one by Morrice.  Thus, while several could be retained at the station, each party in the field was furnished with two, and the measured distance furnished a check, which, in case of discrepancy, that on which greatest reliance could be placed might be ascertained.  It is sufficient to say that the deductions have been in general satisfactory, although the rough motion to which these instruments were subjected in passing through pathless woods, embarrassed by fallen trees and morasses in which the bearers often sunk to the middle, caused changes of rate and even sudden variations.  Uncertainty arising from these causes was rendered less to be dreaded from its being possible to refer, as a base of operations, to the excellent survey of the St. Lawrence River by Captain Byfield, of the British navy.  With the geographical positions given in his charts our own observations agreed so closely as materially to confirm the respective accuracy of both.

24.  The point which in this part of the survey has been kept in view as most important is the determination of the heights.  For this purpose the party of Professor Renwick was furnished with the following barometers: