Two loaned by the Superintendent of the Coast Survey, of his own construction; two portable and one standard, by Neurnan; three of the siphon form, by Buntin, of Paris; one by Traughton & Simms; one by Forlin, of Paris; three of siphon form, by Roach & Warner, of New York; two by Tagliabue, of New York, originally on the plan of Durand, but which had been advantageously altered by Roach & Warner in such manner as to admit of the adjustment of the level of the mercury in the cistern.

The stations at which the lower barometers were placed were Grand Metis until the return of the expedition up the river of that name, and the river Du Loup from that time until the close of the survey.  At these places all the barometers not actually in the field were suspended and registered at the hours most likely to correspond with the observations of a traveling party, say at 6, 7, 8, and 9 in the morning, noon, 1, 5, and 6 in the afternoon, until as the season advanced and the days became short the earliest and latest of these hours were omitted.  Although several barometers were thus constantly observed, no other use of these was made but to determine their comparisons with each other, except one of the barometers of Mr. Hassler, Superintendent of the Coast Survey.  This, from its superior simplicity, being, in fact, no more than the original Tonicillean experiment, with a well-divided scale and adjustment of its 0 deg. to the surface of the mercury in the cistern, was found to be most certain in its results.  All the barometers used by the parties in the field were therefore reduced to this by their mean differences.

The stations at the two above-mentioned places were near the St. Lawrence.  At Metis the height of the cistern of the standard barometer was determined by a spirit level.  At the river Du Loup the height of the station was determined by two sets of observations of barometers, taken with different instruments by different observers, and at an interval of a week from each other.  The results of the two several sets, which were calculated separately, differ no more than 0.5 of a foot from each other.

On reaching the highest accessible points of the streams on which the parties proceeded toward the height of land, stationary camps were established, as has been already stated.  At these series of observations were made at the same hours as at the river stations.  The height of the former was then calculated from a series of observations taken at noon and at 1 p.m. for the whole of the time the camp was occupied.  The heights of the points at which observations were made by the traveling party were then deduced from a comparison with the nearest contemporaneous observations at the stationary camp.  An exception to this rule was made in the observations to the westward of Temiscouata Lake, which were referred directly to those made at the river Du Loup, which was sufficiently near for the purpose.