This detachment accordingly left New York on the 22d May. On reaching Quebec it was found that the proper persons could only be engaged at Trois Rivieres. A delay was thus occasioned before this part of the duty could be performed. The detachment, however, reached Rimouski 4th June, where the snow was still found upon the ground and the river barely fit for the access of boats. No time had therefore been lost, and the reconnoissance of the river was successfully performed. The detachment, after passing all the establishments of lumberers, extended its explorations beyond the remotest Indian paths, and leaving its boats penetrated on foot several miles to the south of the highest point of the stream in which boats could float. In this progress through unexplored ground a lake wholly unknown was discovered. The results of this expedition were embodied in a map, which on examination by parties furnished with better means was found accurate.

It was found by this party that the Rimouski presented difficulties which would forbid its ascent by a party provided with stores and instruments for the prosecution of a survey along the height of land, and that it would be impracticable even to make it the route of an expedition to reach its own source. The little knowledge which was possessed of its upper course and the fact that it had probably never been explored even by Indian hunters were accounted for by its difficulty of access, which would forbid the carriage of a sufficient supply of provisions for consumption during its ascent and descent. On other streams difficulties of this sort had been and were afterwards overcome by the use of the bateaux of the Penobscot, of greater burthen and strength than the birch canoes, but the continual repetition of portages on the Rimouski forbade the use of any vessel heavier than the latter.

2. The main body of engineers, etc., was ordered to assemble in New York on the 15th May, for which time a vessel was chartered for the purpose of conveying them, with stores sufficient for an expedition of five months and the necessary instruments and camp equipage, to Metis, on the St. Lawrence. The experience of the former season had shown that the country was so poor as to furnish little for the support of a numerous party, and it was believed that even game and fish would be found scarce at the points where supplies would be most needed. It was therefore to be chosen between laying in the supplies in New York or in Quebec, and while the great advantage of conveying all the important instruments by sea turned the scale in favor of the former place, it has been ascertained that the decision was in other respects correct, for the dangers and difficulties of navigating the St. Lawrence might have frustrated altogether, and would certainly have materially delayed, the commencement of the main survey.

The sailing of the vessel was delayed, in expectation of the arrival of instruments from Europe, until the 30th of May, when a sufficient supply for beginning the operations arrived.

In the meantime Mr. Lally, one of the first assistants, was directed to proceed to Bangor, in Maine, for the purpose of procuring boats and men to manage them. These were obtained and brought down the Penobscot to Castine, where they were on the 8th June embarked in the vessel which carried the rest of the party, and which had orders to call at that port for the purpose. The experience of the previous year had manifested the great superiority of the bateaux of the Penobscot over all other vessels in the navigation of shallow and rapid rivers. The physical energy and enterprise of the boatmen of that river had also been known. It was believed that it was not only essential that a considerable proportion of the laboring force should be American citizens, but that much good would result from emulation between the boatmen of the Penobscot and the Canadian voyageurs. This expectation was in a great degree confirmed by the result, for although it must be stated with regret that it became necessary at an early period to discharge some of the Americans, the remainder were models of intelligence, sobriety, industry, and perseverance, and entered into the work, not with the feelings of hired laborers, but with those of men who felt that the interest of their country was at stake.

3. The commissioner did not leave New York until 30th of June, being delayed in expectation of more instruments. A part of these only had arrived, but further delay might have been injurious. Proper instructions had been given for setting the party in motion in case it could be organized before he joined it, but these were rendered nugatory by the length of the vessel's passage. This did not reach Metis till 7th July, so that the commissioner, arriving on the 9th, was in time to direct the first operations in person. The stores, boats, and instruments had been landed and partially carried to a camp on the river above the falls. A heavy rain on the 10th July rendered the roads almost impassable, and it was not till the morning of the 12th that the first detachment could be embarked. This was comprised of Dr. O. Goodrich, the assistant commissary, two surveyors, and an assistant engineer. The first was in charge of stores sufficient for six weeks' consumption. The surveyors had orders to survey the river for the purpose of connecting it with the line of exploration, and the latter was directed to make barometric observations. The commissioner and the remaining engineers were detained at Metis by the necessary astronomic observations. These being completed, the instruments, camp equipage, and a portion of the stores were embarked, and the main body proceeded up the river about noon on the 15th July.

4. The river was found to be still swollen by the melting of the snows on the highlands near its source, and, being at all times rapid, the progress of the party was attended both with difficulty and danger. One of the birch canoes, although managed by a skillful voyageur, was twice upset, and one of the heavily loaded bateaux filled with water in a rapid. The result of the first accident was unimportant, except as respected the personal comfort of one of the party, who lost his clothing when it could not be replaced; the second accident caused the loss of some valuable stores. A guide had been procured in the person of a Canadian who was said to have acted in the same capacity to Captain Broughton, who had descended the river by order of the commissioners of Great Britain in 1840. So long as the services of the guide were unimportant he was found intelligent and acquainted with the country, but on passing beyond the region usually visited by lumbering parties he manifested a very scanty knowledge. It had been the intention of the commissioner to ascend to Lake Metis and thence proceed to the height of land by an old portage said to have existed from that lake to the one at the head of the Grande Fourche of the Restigouche, which had been explored by the commissioner in 1840. Lake Metis was chosen because all former accounts, and particularly those of the surveyors of the joint commission under the fifth article of the treaty of Ghent, represented this as the body of water seen to the northwest of the termination of the exploring meridian line. The guide appeared to confirm this impression, and held out inducements that led to the belief that he was acquainted with the portage in question. The nearer, however, it was approached the less seemed to be his confidence. When there appeared to be some reason to doubt his competency or his will, a place in the river was reached where it divided into two branches of nearly equal magnitude. On inquiry from the guide it was ascertained that the easternmost of these was the main Metis, the other the Mistigougeche (Riviere au Foin). Although the latter appeared to be the most direct course to the boundary, it was still believed, and nothing could be learned from him to the contrary, that the former led to the termination of the exploring meridian line. The party of Dr. Goodrich had gone up the Metis, and it was necessary to communicate with it before any change in plan could be made. The commissioner therefore entered the main Metis, and in the evening overtook the surveyors, who had been unable to keep the survey up with the progress of the boats. An express was therefore sent forward to stop the boats, and, the party encamping, astronomic observations were made for the solution of the difficulty in which it appeared to be enveloped. A detachment was also sent out to explore to the eastward of the Metis. This reached the Lake of the Little Red River, and from its banks took bearings to what appeared to be the greatest mountain of the country. This is known by the name of Paganet, and lies to the southwest of Lake Matapediac, forming a part of the highlands which are so obviously described as the boundary of the Province of Quebec in the proclamation of 1763. Its height was reported to be probably 3,000 feet, but as it has appeared in the course of the survey that heights in that region may easily be overestimated, it can not be safely taken at more than 2,500 feet. The result of the astronomic observations seemed to show that the main stream would lead too far to the eastward, and after mature deliberation it was resolved that the course should be retraced and the Mistigougeche ascended. The first part of the operation was attended with little delay. Half an hour sufficed for reaching the forks, whence the party had been six hours in mounting. The guide also stated that the Mistigougeche was a much less difficult stream than Metis. Of the comparative facility, except for a few miles of the latter, no opportunity for judging was obtained; but these were so difficult as to confirm his statement. On the other hand, the former was found to be much worse than it had been represented by him. His knowledge, in fact, was limited to its state in winter, for it appeared from a subsequent interview with Captain Broughton to be doubtful whether he had served in the employ of that officer; and it can be well imagined that the river when locked up in ice should present an aspect of far less rapidity than when rushing with its springtide violence. The Mistigougeche was found to be intercepted by a fall of a few feet, which could not be passed by the boats when loaded, although the Penobscot men boldly and successfully carried theirs up when empty, in which feat they were imitated by the voyageurs, who had at first deemed it impossible. The loads of the boats were carried over a portage, and in this operation the chronometers were found to deviate from each other, showing a manifest change of rate in some or all of them. This may be ascribed to a change in the mode of transportation, but was more than could be reasonably anticipated, considering the shortness of the portage (2,000 yards) and the great care that was taken in conveying them. At some distance above the falls a lake of moderate size was reached, embosomed in hills and embarrassed at its upper end with grass. From the last feature it was ascertained that both lake and river take their epithet of Grassy (Riviere an Foin, and, in Indian, of Mistigougeche, or Grassy Lake). At this lake the party of the commissioner was in advance of the loaded boats. A halt was therefore made and a party sent out to explore to the westward. This party reached an eminence whence a lake was seen, which the guide stated to be the head of a branch of the Rimouski, far distant, as he averred, from any waters of the Restigouche. Subsequent examination has shown that this party had actually reached the height of land and that the survey of the boundary might have been advantageously commenced from this point.

On leaving the lake the river was found to have a gentle current for a few miles. It was then interrupted by a bed of timber, after passing which it became as rapid as ever. In a short time, however, a noble sheet of water was reached, surrounded by lofty hills, and of great depth. At the upper end of this a place was chosen for a stationary camp, and preparations were made for proceeding to the land survey. While these were going forward with as much dispatch as possible, Mr. Lally, one of the first assistants, was detached to reconnoiter the inlet of the lake. During his absence observations were taken and the rates of the chronometers worked up. Of the four instruments with which the expedition was furnished, two had varied from the other two on the portage. All were of good reputation, and no means existed of determining on which pair reliance could be placed. From the rates of two of them it appeared that the camp was situated 12 miles to the northwest of the tree chosen by the American surveyors in 1818 as marking the northwest angle of Nova Scotia. Actual survey has shown that the distance is about 10 miles. The result given by the chronometers was speedily confirmed by the return of Mr. Lally, who reported that he had actually reached the marked tree, well known to him by his visit to it the year before, and that he had pursued for a couple of miles the line cut out subsequently by Captain Broughton.

6. The preparations being completed, Messrs. H.B. Renwick and Lally were sent out, each at the head of a sufficient party, with instructions to proceed together to the west until they reached waters running to the Restigouche and then to divide, Mr. Lally proceeding to the northwest angle and Mr. Renwick toward Rimouski. Each was directed to pursue as far as possible the height of land and to remain in the field as long as the supplies which the men could carry would permit. They were also ordered to mark their path in order to insure a safe return, as well as all the stations of their barometric observations. Bach of the laborers was loaded with 56 pounds besides his own baggage and ax, and the engineers and surveyors carried their own baggage and instruments. The commissioner, with one assistant, remained in the stationary camp for the purpose of determining the longitude accurately and of making corresponding barometric observations.

7. In this place it will be proper to state that the lake which was thus reached was ascertained with certainty to be that seen by the surveyors of the joint commission in 1818, and which was by them supposed to be Lake Metis. As it has no name yet assigned to it, it has been called upon our maps Lake Johnson, in honor of the American surveyor by whom it was first visited. It is 1,007 feet above the level of the sea, being more than twice as much as the total fall assigned to the waters of the Metis in the report of Messrs. Mudge and Featherstonhaugh. So great an elevation in so short a course is sufficient to account for the great rapidity of the stream. To illustrate this rapidity in an obvious manner, the birch canoes, which on the waters of the St. John are easily managed by one man, are never intrusted on those of the Metis to less than two. Our departure from Metis in boats so deeply loaded, as was afterwards learned, was considered there as a desperate attempt, and although but one of them sustained injury, this is to be ascribed to the great skill of the boatmen; and to show the velocity of the stream in a still stronger light, it is to be recollected that, after deducting the loss of time on the Metis, nine days of incessant labor were spent in taking up the loaded boats, while the assistant commissary whom it became necessary to send to Metis left the stationary camp at 2 o'clock in the morning of the 28th July and reached the mouth of the river before sunset of the same day, after making two portages, one of 2,000 yards and the other of 2 miles.