llond 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:

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, no