because it runs from a station 574 on 635-the end of the line to a previous station, viz., 34 on 485, which was the starting point; this line is 716 long; mark this distance against it. Thus far these are all loose lines, and might lie in any position.

The next measured line, however, ties them in, it begins at 34 on 485 (the base line), and runs to another previous station, 719 on 724; its total length is 873, and there are two stations upon it, 230 and 490; draw this line in its proper position, and mark off the stations, 230 and 490.

The next two lines are check-lines, the one (471) runs from 490 to 574 on 635; the other (3.67) from 230, to 480 on 485; mark these also.

Having placed these several lines roughly with their given lengths, in their supposed position, proceed to plot them off correctly by triangles, marking in every case, on the plan, the direction the line was measured in on the ground (see plate 1). AB, of course, is the base of the whole. Upon AB lay off a triangle, whose other two sides are 7.19 and 8.73; that is, from 0.34 as centre at the distance 8·73 chains describe an arc, and from 4.80 as centre, at the distance of 7.19 chains describe another arc intersecting the former; complete the triangle and mark upon 8.73 the stations 2.30 and 4.90. Then, to verify the correctness of the work thus far, measure the distance of the station 2.30 from the point B; this, if the work be correct, should be 3.67, the length of the check line.

Next, upon the line 873, lay off another triangle, whose sides are 574 and 7·16; the distance of the previous station 490, from the vertex of this triangle, should, if the work be right, be found 4.71. The whole field is now plotted.

EXAMPLE 2.

Method of Surveying and Plotting Two Fields Together.

The field in the previous example having been already surveyed, the adjoining field was added to it, which is to be plotted from the accompanying field notes.

Having the previous notes of Field No. 1, the following notes were taken for the survey of the adjoining Field No. 2.

Plotting of the Notes to Field No. 2.

The first line measured is 609, it begins at 7.19 on 7.24 which is produced to obtain this distance. Produce the line 7.19 therefore to 609 further, which is a station-then, turning to the right, agreeably to the field book, mark off the distance 685, which is the station point in the next line 731 from this point 685, the distance to a known corner in the first field (being 574 on 635), is 690.

Now, 574 on 635 is a known fixed point, and because the line 7.19 of the last survey, is a fixed line, its production is also fixed, and the end 609 is a fixed point; the line joining 5.74 on 635, and this point, is, therefore, also a fixed line. Measure this diagonal line by the scale, and see if its length is 8.68 as it was made in the field, if it is, the whole of the work thus far is right; then its distance, determined in position by joining two fixed points, is checked by its measured distance. Upon this base, therefore, describe a triangle, whose other two sides are 685 and 690, and their intersection is also a fixed point.

Again, by taking the distance 500, upon the diagonal 8-68, and measuring the check line 535, this line, measured from a point in a fixed line, to the intersection of the two other lines, becomes a check upon this triangle.

Having found the plotted check-lines agree with the measured distances, (which shews, that both field and office work are correct,) draw in these chained lines carefully, in red ink, and proceed to lay off the offsets.

To lay off the Offsets.

A little attention to this subject will be found useful to the student afterwards.

Take the first Field.

The offsets on the line AB, are all to the left; mark off, therefore, the several offsets in their proper places, observing

D+

in the second offset, that (10+10) is ten links up to the hedge, which, with the ditch, is ten links wide. Mem: Whenever these offsets are referred to in pairs they must invariably be read if they are left hand offsets, from right to left, and vice versa. They are placed here exactly as they

E

stand in the notes. This determines the position of the

D

hedge to be within the field; without the 10, or had it been (D+10), the hedge would be beyond the boundary of the field. At 4.85, the cross ditch of the field intersects the line.

In the next line the offsets are still to the left, and are marked (D+5), showing that, in this case, the hedge is without the field. At 7.19, there is an offset of 8, to where the edge of the side ditch intersects the side of a pond; at 7.24 the cross ditch of the field intersects the line as before. The width of the pond 40 links, and its length 40 links, are marked.

In the next line, the offsets are still to the left, and the (D+5) shows, that the hedge, in this case is beyond the field. As this line, if produced, will cross Maiden Lane, it is produced across for the purpose of determining its width and position. In every case, in addition to the mere measurement of the field, it is advisable to annex such collateral localities as roads, turnpikes, ponds, &c., as may determine the relative position of the field. At 0.08 there is an offset of 8 links (on the left) to the second gate post. In the following line 716, where the offsets "are still to the left" at 392, there is an offset of 22 to "gate post " only. Observe that it is usual to take to the first gate post, and allowing the average width of gate to be 15 or 16 links, or about 10 feet, to determine the position of the gate by the direction of the line. It is difficult to fix the position without some fixed rule, such as the above, of always taking the first point of the gate, as you come to it, on the line, whence the offset is taken.