To measure a straight line with the chain.

In measuring with the chain, it is requisite to have ten small arrows, or pins of strong iron wire, about a foot and a half long, and pointed at one end, to stick in the ground.

A piece of red cloth should also be tied to the ring of each arrow, so that they may be more easily perceived in the midst of grass or underwood.

The surveyor should also be furnished with some half dozen poles six feet high, about an inch diameter, pointed and shod at the bottom, and having a white and red flag, about nine inches square at the top.

Important observations to young beginners.

Having previous ranged the line carefully with these flags, of which there should be at least three to every long line, let one assistant take the lead, who is called the leader, having the ten pins and the chain-handle in his left hand, and proceed toward the mark at the end of the line; while the other assistant, called the driver, holding the other end of the chain also in his left hand, keeps it close against the mark or starting point; when the leader has come to the end of the chain, let him turn round with his face towards the driver, and, taking one of the arrows in his right hand, let him pull the chain tightly, keeping it on the ground, and put down the arrow he held in his right hand close against the chain-handle outside.

As the chain is seldom straight at first, when the leader faces the driver, the driver must always keep his end to the ground, close to the mark; but the leader, previously to finally setting the arrow, should raise the chain with both

hands, shake it to the very end, and before he puts his arrow down, see that it is perfectly straight.

The leader must also observe, as he is putting down the chain, to look towards the driver, to see if he is himself in the right direction, or whether the driver is noting him to the right or to the left; when he has succeeded in hitting the right direction (which he knows by the driver calling out "down"), and, obtaining the proper measurement of the chain, by carefully complying with the directions above, and has put his first arrow down, he must return the cry of "down" to the driver, and, taking the chain up in his right hand, must proceed onward until the driver, coming to the first arrow, cries out "stop," when the same process is repeated. The leader having a second time. returned the cry of " down," the driver picks up the arrow, carrying it in his left hand, taking care, as long as he has two or more flags to cover before him, to direct the leader; when the leader, however, has past all but the last flag, the proper position of the arrows depends upon himself, which he must carefully do, by covering the backward flags.

When the leader has put down the ten pins, he calls out tally," and the driver, dropping his end of the chain, comes up to the place, picks up the last arrow put down, counts over the whole of the arrows, and, putting his foot to the mark, returns them again to the leader, who finding they are the right number (10), proceeds with the chaining as before; the second "tally" is then called; then the third; each cry to prevent mistakes, being repeated by the driver. The surveyor should also enter each tally in his book.

In this manner they continue, till the whole line is measured. Should it not be a complete chain to the end,

and no offsets required to be taken, it is usual for the leader to put his end of the chain down to the mark, and for the driver to read off the distance; but if there are offsets, then the driver had better put his end down, and the leader pull up, as the position of the offsets is measured from the driver's end.

CHAP. II.

THE OFFSET STAFF.

(For the Chain.)

Is a narrow slip of deal about 11⁄2 inch wide by 1 inch thick, and generally 10 links long, divided into links; it should be furnished at one end with a small notch or hook, to put the chain through the hedges, and be numbered on both sides, from different ends. It is used for the purpose of measuring short distances, called offsets, from the line to the hedges, &c.

As these offsets must be measured at right-angles to the chain, the surveyor should stand on the opposite side of the chain to the hedge, or object to be measured to, and walking along the chain, looking at either end, mark where a perpendicular from the given object would fall upon the chain.

CHAP. III.

ON THE CROSS STAFF.

THE cross staff is about 5 feet six inches high, pointed, and strongly shod, to drive into the ground, having at the top a circular piece of hard wood, so fixed as to be taken on and off.

The wood head is divided into four divisions, by grooves, at right angles, cut about half an inch down into the wood, which is about 2 or 2 inches thick. This head is sometimes made with a spring, to move up and down the pole of the staff, and to remain firm at any height.

It is always necessary to test the accuracy of these grooves, which can be done in the following way :

a

Let ABCD be a cross staff; and AD, BC, its sights, or grooves; place a flag, a, in the direction of the groove AD, and another at b, in that of BC; half reverse the cross, so that DA point to b, and CB to a. Then, if the flags are still in the direction of the grooves, the instrument is correct.

The principal use of the cross staff is in the measurement, by perpendiculars, of straight-sided fields; in the setting off of short perpendiculars from a base line; and in the laying out of streets and building lots.

It is useful where no great accuracy is required, when, in the computation of the areas, it is not requisite to take

D

into account the irregularities of the hedges, as, in surveying a field, it saves the necessity of measuring the whole way round, and makes a diagonal, with two perpendiculars from each of the opposite corners, all the admeasurements required.

This instrument was much more in use formerly than it is now, though country surveyors still have recourse to it, when they are employed in measuring farm crops, &c.

CHAP. IV.

THE FIELD BOOK.

THE field book should be of a convenient size for the pocket, having the left page ruled with a central column, and the right page left blank for remarks. The central column should be headed "Chains," on either side " Offsets," and the right page "Remarks."

The central colunin is intended for all actual lines measured, and, by commencing from the bottom of the page, the page becomes a smaller representation of the reality with the line measured from you, and the offsets, at their respective distances on that line, taken at so many links to the right or to the left, as are actually on the ground. In keeping the field book, it should always be remembered, that the central column is virtually but one line, representing the chain, the space within the column being merely