In order to obtain a correct profile or vertical section along the whole extent of this meridian line, in the hopes of furnishing data for accurate comparisons of elevations so far as they might be considered relevant to the subject in dispute between the two Governments, and also to afford an accurate base of comparison for the barometers along an extended line which must traverse many ridges that will be objects of minute exploration for many miles of lateral extent, an officer was detailed to trace a line of levels from the base of the monument marking the source of the river St. Croix to tide water at Calais, in Maine, by which means the elevation of the base of the monument above the planes of mean low and mean high water, and also the elevations of several intermediate points of the river St. Croix on its expanded lake surface, have been accurately ascertained.

Another officer was at the same time charged with tracing a line of levels from the base of the same monument along the due north line as marked by the commissioner, by which it is intended that every undulation with the absolute heights above the plane of mean low water at Calais shall be shown along the whole extent of that line.

At Parks Hill, distant only 12 miles from the monument, a second station for astronomical observations was established, and a camp suitable for that purpose was formed.  On the 26th day of October, whilst occupied in completing the prolongation of the meridian line to that point and in establishing a camp there, the party was visited by a snowstorm, which covered the ground to a depth of 4 inches in the course of six hours.  This was succeeded by six days of dark, stormy weather, which entirely interrupted all progress, and terminated by a rain, with a change to a milder temperature, which cleared away the snow.  During this untoward event the parties made themselves as comfortable as practicable in their tents, and were occupied in computing many of the astronomical and other observations previously made.

On the 2d of November the weather became clear, and the necessary astronomical observations were immediately commenced at Parks Hill.  From this elevated point the first station could be distinctly seen by means of small heliotropes during the day and bright lights erected upon it at night.  Its direction, with that of several intermediate stations due south of Parks Hill, was verified by a new series of transit observations upon high and low stars, both north and south of the zenith.  By the same means the line was prolonged to the north.

In one week after commencing the observations at Parks Hill the weather became again unfavorable.  The sky was so constantly overcast as to preclude all astronomical observations, and the atmosphere so thick as to prevent a view to the north which would permit new stations to be established with sufficient accuracy in that direction.  Unwilling to quit the field while there was a prospect of the weather becoming