some kind of a field book must be used, in which a register, or account of whatever is done and occurs relative to is to be entered.

the survey,

This book each surveyor forms and rules for himself, as he thinks best. The following is a specimen of a form much used. It is ruled into three columns; the middle or principal column is for the stations, angles, bearings, distances measured, &c. and those on the right and left are for the offsets on the right and left, which are set against their corresponding distances in the middle column; as also for such remarks, as may occur, and be proper to be noted in drawing the plan, &c.

Here is the first station, where the angle or bearing is 105° 25'. On the left, at the distance of 73 links in the principal line, is an offset of 92; and at 610, an offset of 24 to a cross hedge. On the right, at O or the beginning, an offset 25 to the corner of the field; at 248 Brown's boundary hedge commences; at 610 an offset 35; and at 954, the end of the first line, the O denotes its terminating in the hedge. And so on, for the other

stations.

A line is drawn under the work at the end of every station line, to prevent confusion.

But some skilful Surveyors now make use of a different method for the field book; namely, beginning at the bottom of the page they write upward, sketching a neat boundary on each hand as they pass along. An example of this method will be given under the Problem, which requires the survey of a large estate.

In smaller surveys and measurements, a good way of setting down the work is to draw, by the eye, on a piece of paper a figure resembling that, which is to be measured; and to write the dimensions, as they are found, against the corresponding parts of the figure. And this method may be practised to a considerable extent, even in the larger sur

veys.

PRACTICE OF SURVEYING.

THIS part contains the several operations proper to be performed in the field, or the modes of measuring with all the instruments, and in all situations.

PROBLEM I.

To measure a line or distance.

To measure a line on the ground with the chain; being provided with a chain and ten small arrows, or rods, that one one may be stuck into the ground, as a mark, at the end of every chain, two persons carry the chain, one at each end of it, and all the ten arrows are taken by one of them, who is to go foremost, and is called the leader; the other being called the follower, for distinction.

A picket, or station staff, being set up in the direction of the line to be measured, if no mark appear in that direction; they measure in a straight line toward it, the leader fixing in the ground an arrow at the end of every chain, and the follower always taking it up, till all the ten arrows are used, and in the hands of the follower. They are then all returned to the leader, to be used again. And thus the arrows are changed from one to the other, at every ten chains' length, till the whole line is finished; then the number of changes of the arrows shows the number of tens, to which the follower adds the arrows he holds in his hand, and the number of links of another chain from him to the mark or end of the line. So, if there be three changes of the arrows, the follower hold six, and the end of the line cut off 45 links more, the whole length of the line is 3645 links.

When the line is on a declivity, ascending or descending, at every chain's length apply a small pocket level, or King's quadrant, to the chain, that it may show how many links the slope is longer than the corresponding level line, and correct the length.

1. With the Plane Table.

The table being covered with a paper, and fixed on its stand; plant it at the station A, and fix a fine pin, or a point of the compasses, in a proper part of the paper, to represent the point A. Close by the side of this pin lay the fiducial edge of the index, and turn it about, still touching the pin, till one object B can be seen through the sights; then by the fiducial edge of the index draw a line. In the same manner draw, another line in the direction of the other object C, and it is done.

2. With the Theodolite, &c.

Direct the fixed sights along one of the lines, as AB, by turning the instrument about till you see the mark B through the sights; and there screw the instrument fast. Then turn the moveable index about till, through its sights, you see the other mark C. by the index, upon the graduated limb or ring of the instrument, shows the quantity of the angle.

Then the degrees cut

3. With the Magnetic Needle and Compass.

Turn the instrument, or compass, so, that the north end of the needle point to the flower-de-luce. Then direct the sights to one mark, as B, and note the degrees cut by the needle. Next direct the sights to the other mark C, and note the degrees cut by the needle. Then their sum, or difference, as the case is, will give the quantity of the angle BAC.

4. By Measurment with the Chain, &c.

Measure one chain's length, or any other distance, in both directions, as to b and c. Then measure the distance bc, and it is done. This is easily transferred to paper, by mak