In order to set out the allotments; of land in countries which, like some parts of North America, are covered with wood, the surveyor determines on the ground the position of a boundary-line comprehend ing an area of a square form, each side of which is six or eight miles in length. One of these spaces, which constitutes a township, is usually divided into squares of one mile on each side; and again, these arc divided into squares of half or a quarter of a mile on each side.
The boundary-line of the township is determined by measuring with a chain a base-line six or eight miles in length, generally along one side of a square already marked out for some previous township ; and at each extremity of this line carrying out one of equal length perpen dicularly to the base. A line joining the farthest extremities of the last lines completes the square. In order to mark out the two sides which are perpendicular to the measured base, a circumferentor, or a large surveying-compass, furnished with plain " sights," and mounted on a stand, is used. The bearing of the intended line from the mag netic theridian being ascertained from the position of the base, and the instrument being set up at one extremity of that line, the line of the sights is turned so as to make with the needle of the compass an ang equal to that bearing ; then the surveyor, looking in the direction the sights, observes some remarkable tree, and causes the distance fro his station to that tree to be measured, small trees, if such there 1 between himself and the object, being cut down. Notches are cut
the tree in order that it may be distinguished from the others, and tl instrument is removed to the opposite side of the tree. The line ( the sights is then turned so as to make the given angle with tl needle, and the distance of the station to the next remarkable tree i the line is measured as before. This process is continued to the extr mitt' of the line which is to be set out, and strong stakes are phinte at the end of each mile, half mile, and quarter mile on the line. Fro' these stakes the lines of division and subdivision are carried out in similar manner.
When the allotments are contiguous to a road, or the bank of a rive a narrow front is measured along the road or river, and the boundar3 lines are carried nut, perpendicularly to the front, as far as may b requisite in order to comprehend between them the intended area.