the connecting links, or, if short, by straightening the wire links.

It may be stated that a Government standard of all kinds of English measures has been established in Trafalgar Square, by means of permanent bronze marks, let into the granite plinth of the terrace wall in front of the National Gallery. There is also a standard in the Guildhall, belonging to the Corporation of London; and in nearly every city and town in the kingdom, the Borough Surveyor has arranged certain marks wherewith to test his chains, and these, on a courteous request, will doubtless be put at the service of any surveyor whose avocations may call him into the neighbourhood. There is an art in doing up and throwing out the chain. In the former case, the chain should be taken at its centre (with the

circular tablet) and gradually each pair of links towards the end should be cylindrically folded diagonally over the last until the handles are reached, so that when tied up, the chain represents

almost a wheatsheaf. The accompanying sketch (Fig. 10) shows the chain folded up and the arrows.

In throwing out, the handles should be held in the left hand with a few links loose, whilst the rest of the folded chain is held with the right, and by this means thrown smartly away, retaining hold of the two handles.

Chain-men. Now, in all chaining operations, there is one person to drag the chain, called the leader, and another to follow, called the follower. Of these two (supposing two men are employed to assist the surveyor) the follower should be the more intelligent and trustworthy.

I would here say, that in all organised surveys there should always be ample assistance. I mean, that two men at least are requisite, so that the surveyor may be free to make observations, sketch, and enter measurements in his field-book, and generally superintend operations. Indeed I go further, and express a firm conviction, that it is real economy to have a third man, or an intelligent lad, to fetch and carry rods, to take charge of plans, books, &c., and generally to act as aide-de-camp.

Leader's Duties.-Reverting to the leader and follower, it is necessary to instruct each in their respective duties. To the leader should be explained, that, at the commencement of work he is to receive (and count for his own satisfaction) the arrows, for

DUTIES OF CHAINMEN.

II

which he will be held responsible. His duty is to precede the follower in a direction indicated, and to draw the chain gently after and upon reaching the limit of its length, he is to turn half round to face the follower, holding the handle of the chain in his hand, with one of the arrows between the outside of the handle and the inside of his hand thus (Fig. 11), and to watch for a signal from the follower

as to how he should move laterally right or left, taking care (on his part) to keep the chain straight, by gentle shaking up.

Arrow

1 LINK

Fig. 11.-How to hold Chain.

Some surveyors hold that the leader should completely face the follower at the end of each chain, but my experience has been that, by so doing, his body often obscures a forward point, and by very little practice, he can be made to do the work as well sideways. It is necessary that he should hold the arrow perfectly upright, and only move it gradually right or left, so as to mark the exact spot indicated by the follower.

Here I may say, that it is useful to range out several points in a line by means of laths or whites, which will be useful in guiding the leader to keep in the direction it is necessary to go. The surveyor must impress this upon him, as I have sometimes found that the leader will elect to walk in a certain direction, apparently to his own satisfaction, which has the disadvantage of being considerably out of the line.

Duty of Follower.-The duty of the follower, having previously had the destination of the line explained, is to retain the other end of the chain in hand, and to direct the leader as to the direction he should take; to call out when the chain is at its full length; to hold the extremity of the handle against the centre of the station whence the line starts, or against the arrow which had been previously placed in the ground (taking care to hold the outside of the handle against the point); to see that the chain is stretched perfectly straight and lies evenly in a true line with the forward station; to direct the leader to move his body altogether right or left, and when approximately in line, to instruct him by slight lateral movement of his hand, right or left, until the exact point is obtained. If within hearing range he should call "To you" or "From you," or if beyond earshot, by moving the head right or left; and to convey to the leader that he is right, and it is necessary to fix an arrow in the ground to mark the spot, either call out Mark," or convey that meaning by a nod.

66

In the event of it being found impossible to make the leader hear your directions or those of the follower, if you want him to move to the right, waive your right arm backwards and forwards, and, if to the left similarly with your left arm; and to indicate that he is in a right position, bring both arms smartly to attention.

How to use the Chain.-It should here be explained that as the chain measures 66 ft., or 100 links, between the ends of the handles, it would not be right to hold one extremity against the arrows or pegs at each end, for, by so doing, the length of the line is diminished by the number of half-thicknesses of the arrows or pegs, corresponding with as many chain-lengths as have been measured. But when pegs are used, if the end of each handle is held in the centre—or with arrows, if the leader holds the inside of his handle against the arrow, whilst the follower holds his handle (outside) against the arrow at his end-by these means the proper length may be adjusted.

After placing an arrow in the ground at the end of the first chain, the leader proceeds in direction of the goal, until he has reached the limit of the chain. The follower, having walked to the first arrow, and held his end of the chain thereto, now directs the leader so as to mark the second chain, which having been duly accomplished, the men go forward (the follower having previously picked up the first arrow), and so they continue, until the leader has expended all his arrows, when, having placed his last in the ground he calls out "Ten," which should be acknowledged by the surveyor and booked accordingly. The surveyor now proceeds to the tenth arrow, and putting his offset staff in the place of the tenth arrow, the follower, having reached this point, picks up the tenth arrow, and, with it counts the ten arrows, before handing them over to the leader, who on his part, again counts them to see that he receives the right number.

The foregoing is a description of the method of chaining a simple line between the points, supposing it to be necessary only to ascertain the length of a line, but it seldom happens, even in a check

3rd.

4th. Chain

Chain

10 20 30 40 50 60 70 80 90

line, that such an operation can be performed without crossing through hedges or fences of some description.

Fig 12.-Chaining through Hedges. Crossing Hedges, &c. (Fig. 12).-In these cases the leader and follower must wait before moving forward, to allow the surveyor to note the chainage of such intersection. For instance, if after three chains have been measured a hedge intervene between the third and

fourth chain, then the follower, noting at what point the leader's end of the chain should pass through the hedge, gives the necessary directions, which having been done, the chain is now pulled tight, and a fourth arrow having been adjusted in place, the chain is allowed to rest until the number of links is ascertained where the fence crosses the chain. In the case supposed (Fig. 12) the number of links is 47, so that the crossing of the hedge on our chain-line should be booked 3.47ths.

Hedge and Ditch.-Here it may be well that I should speak of hedge and ditch, which appears to be a question somewhat enveloped in mystery. If I stand

Ditch

B

in a field with the ditch on my side of the hedge, then I know that the field in which I am standing reaches only up to the edge of that ditch, and that both the ditch and hedge belong to the field on the other side, as per sketch (Fig. 13). Thus the boundary of A is the edge of Fig. 13.-Boundary of Field. the ditch on the left, whilst the ditch and hedge belong to B. In illustration of this, when a railway is staked out through a district, it is usual for the contractor to fence in the land required for the works by means of what is called a "post-and-rail fence" (see Figs. 14 and 15), which represents the extremity (on either side) of the property acquired by the company; and one of the last things done before the completion of the railway, is for the contractor to cut a grip or ditch, on the inside of the fencing, and with the excavated soil to form a mound in which "quick" are set. The life of the larch post-andrail fence is supposed to be long enough to enable the quick to develop into a hedge. And in future years, when decay shall have re

Centre of

Railway

Fig. 14.-Boundaries.

Centre of

Railway

Limit of

Boundary

Fig. 15.-Boundaries.

Post and

Rail Fence

moved the wooden fence, a surveyor will make the necessary allowance outside the hedge for the real boundary of the railway.

How to measure Fence.-Here I would say, that it has been found to be more convenient to take all measurements to the centre, or root, of the hedge, and to make the necessary allowance

for the edge of the ditch therefrom. The usual allowance is six links, but in different counties in England this length varies according to custom, and it will be prudent of the surveyor to make inquiries in the locality as to that custom. This allowance of six links is, of course, upon the square-as A B (Fig. 16)

-for, if the chain crosses in an oblique direction (as c D) then the distance will be greater. For instance, suppose the edge of the ditch on the square is six links, as A B, but the chain crosses instead at an angle of 30°,

then the length from the hedge to the edge of the ditch will be twelve links instead of six.

Foot-set Hedges.—It may happen that a hedge has a ditch on either side, or none at all, and yet divides two properties, and in such a case the centre or root of the hedge should be taken.

Offsets. The process of surveying, after the necessary lines have been laid out, consists of determining the various boundaries, buildings, &c., by means of lateral measurements, to such points right or left of the chain-line, as may distinguish any alteration in shape of the fence, or the angles of the buildings.

These lateral measurements are called offsets, and strictly speaking are always taken at right angles to the chain-line. As it is possible upon the ground, no matter how uneven, to lay out a straight line, which on paper is drawn with a pencil and straightedge, so it is possible also upon the ground to set out a right angle. Under the head of " Instruments" (Chap. III.) I have described the cross-staff (p. 29), and optical square. I have described these appliances for setting out a right angle; and for taking offsets the laths will be found to be the most useful and accurate. But for general work, the surveyor soon gets accustomed, with the eye alone,

to find the exact position on the chain at right angles to any clearly defined point. A greater help is to lay down the offset staff, and place it as nearly perpendicular as it is possible to judge, and then, looking along the rod, to mark with the eye any point in line therewith in the fence, as shown by the dotted line D E (Fig. 17)