object; this will ensure his being, at the chain's length, not very far off the line. If he is not at once persistently drilled into this, instead of being only a foot or a few inches off the right line, one way or the other, he will be generally many feet, perhaps yards, out of the true direction. When so far off, he will have to move many times backwards and forwards, as directed by the follower, before he will be on the line, by which time is lost at every chain; and when this is repeated two or three hundred times in the course of the day, sometimes a great deal more, it will at once be seen that it absorbs a very considerable portion of the working day. But if, on the other hand, he is at once taught to keep his eyes on the forward object, as he drags the chain along, he will, at the chain's length, almost always find himself within a foot or so of the mark, when a very few directions will bring him correctly on to the line.

When the leader has come to the chain end, he should turn half face about, so as to stand with his right side towards the follower, holding the end of the chain and one arrow in his right hand, and this arrow he should hold at not more than five or six inches from the point end. This will ensure the chain laying flat enough for all practical purposes, if the follower at the same time holds his hand down to the ground, and close to his arrow. The follower should then hold his chain-end and arrow out before him, so that his body be not in the follower's line of sight. He should not at first stick his arrow into the ground, but hold it an inch or so off the ground, until he finds, by the given directions, that he is getting very near the right spot. On the follower's calling out "mark," the leader drives the pin into the ground when the chain is laid.

The next thing to be very careful of is, that the leader holds his arrow perfectly upright; until well drilled to his work, he is too apt to lean his arrow slantingly forward, so that correct chainage is not obtained. This generally arises from the follower leaving the leader to straighten the chain by tightening or pulling at it; this should not be; the follower should be taught to straighten the chain himself by gently casting it one side or the other as may be required, and he should not be allowed to call out to the leader, "straighten the chain," or "tight," which means the same thing, the leader having already quite strain enough on his arm by having to hold out the chain and pin sideways.

In the next place, with regard to the manner of the follower giving directions to the leader so that the latter may stick his arrow on the right line; it is too much the custom to allow the follower to give signals to the leader, either by waving his hand

OBSERVATIONS AS TO LEADER AND FOLLOWER.

7

right or left, or working his head in those directions; nothing can be worse, as it compels the leader, who is stooping and holding out his hand loaded with the arrow and tight chain, to twist his head round to see the follower's signals, and consequently to have his eyes off his arrow, so that it may slant backward or forward without his being aware of it; besides it is unnecessarily fatiguing. The follower should be taught to signal to the leader by calling out "to you," or "from you," as the position of the arrow may require; the leader has then a better command over the chain; he can keep his eye on his arrow, and see that he holds it upright.

We must now say a few words as to being over cautious or too fastidious in getting the arrow exactly on the line; in doing this, however, we must particularly request our readers not to imagine that we in any way advocate slovenly surveying, which in engineering matters particularly is absolutely worthless; at the same time, however, a great deal of time may also be uselessly expended in "picking out pins' points." Perhaps one of the best illustrations we can afford as to our meaning, is a chain at the time of being used in chaining across a field freshly ploughed up, or through a field of wheat, clover, turnips, &c.; now, not all the pulling and casting we can give, will lay the chain perfectly straight; again, observe the innumerable little undulations in the surface of the ground which are met with at every chain's length, and are but just perceptible; these latter obstructions affect the chainage vertically as much as the former do horizontally, and both occur at every chain nearly throughout a survey. Now the same amount of irregularity may be allowed as regards the exact position, mathematically speaking, of the arrow. The result, as affecting the true chainage, will be found for all practical purposes inappreciable, more particularly as regards hedges and ditches, and all ordinary boundaries. When we come to the survey of streets and buildings to a scale of thirty or forty feet to one inch, it is another matter; but of this we shall speak in another place. To return to our present subject, and further to illustrate our meaning, let the reader measure over three or four times a line of thirty or forty chains, at first attending minutely to the position of the arrows, and so measuring it twice over; and next let him measure again twice over, neglecting within the bounds of common sense this minutely correct position of the arrows, and keep notes of all the four measurements; he will find that the differences are utterly inappreciable, and that there will be, in all probability, as much difference between the first and second, and between the third and fourth measurements, as between.the first and third, or second and

fourth. Possibly the reader may now inquire the motive of this lengthy explanation of a matter apparently trivial; to this the answer is, to prevent the young surveyor wasting his time, for waste it is, since the result of this over caution, against which it is now the object to warn him, cannot, in fact, be in the least degree practically appreciable. If, on the other hand, he chooses to give this advice an extreme meaning, he will have the mortification to find in the end that his survey is of no value for engineering purposes. As we have said before, nothing will better satisfy the mind as to the true sense and extent of our meaning than measuring a line a few times over, and comparing the results.

Never in chaining allow the chain men to cast the chain over a hedge, but always through. The only exception that I can think of to this general rule is, where the ground is very abruptly rising on one side or the other of the hedge. Before reaching a hedge, the follower should very carefully note the spot on the line where the chain should pass through the hedge, and, although the brow of the ditch is the boundary of a field or property, and is to be noted as such in the field-book, it is also very advisable to note also the centre of the hedge carefully whilst the chain is held tight; by doing this, and at the same time cutting a little bark with a knife off one or two branches near the ground, we have always the means of finding a well defined spot on the line, both as regards position and measured distance. Such marks as these will remain a long time after "stations" proper have been effaced by accident or mischief.

There is another practical hint as regards hedges which we would venture to give the student, and even to some surveyors. It is to avoid cutting down hedges unnecessarily and indiscriminately. We have often seen a gap cut in a hedge wide enough to drive a wagon through-to say the least of this it is sheer waste of time; such acts of mischief enrage the farmers, who consequently turn the surveyor off; and although he may come back again in a day or two, it occasions another loss of time. Again, if it be found necessary to clear the view through a hedge, never cut down any of the main branches, but merely the leaves and twigs which obscure the sight; in a year or so these will all grow again, and the damage disappears; but cut away any of the main branches, and a handsome quickset hedge is disfigured for years afterwards. For every reason, therefore, it is advisable to avoid cutting gaps through hedges, at least as a general rule, though necessarily many exceptions will occur. In going up or down sloping or "sideling" ground, it will be

SLOPING GROUND-INCLINOMETER.

9

observed that if we measure the inclined length we do not obtain the horizontal length, which is that which we require for laying down the plan of the survey on paper; for instance, in the annexed figure, A B is the inclined length measured along the sloping ground; but AC is the horizontal

B

A

length required for laying down the plan on paper; for many ordinary purposes, and where the inclination is not great, we may obtain the horizontal measurement by holding up the chain at one end, whilst the other is held close down to the ground, as shown in the dotted lines, taking care as much as possible to prevent the chain from bagging, and also that the arrow is placed vertically under the end of the chain which is held up off the ground. When the inclination is sufficiently great for the vertical height at which one end of the chain is held from the ground to amount to three or four feet, and particularly if there are several chains of such ground to measure over, it is well to observe further precautions. All the chainmen should be provided with five or six feet of line, and something in the shape of a plummet, even if it be only a stone at the end of the line. By holding this in his hand instead of the arrow, the leader ascertains in sloping ground where the arrow should be placed, and the follower by the same means, supposing he has to keep his end of the chain up-raised by keeping his plumb near the arrow, is enabled to hold his chain-handle exactly over it. By these means the horizontal base of very steep inclinations may be obtained, even if each chain's length has to be measured by the above means in several steps, which is the reason of the technical expression "stepping," which is applied to this method of chaining; and where it does not exceed two or three chains, and these precautions are carefully resorted to, the work will come out very well. When, however, there is any length of sloping ground, and the inclination is considerable, recourse should be had to an "inclinometer," which is an instrument for measuring the angles of elevation and depression, and ascertaining the corrections to be made in order to obtain the true horizontal distance. Instruments of this kind are to be obtained from the makers of mathematical instruments. At the end of this volume the reader will find a plate, entitled "inclinometer," illustrating the instrument the author has been in the habit of using, and which is very easily manufactured. At one end, through the brass rim enclosing the semicircle, is an opening of about a quarter of an inch in diameter, with a fine wire stretched horizontally across, coinciding with the diameter AB of the semicircle; at

the other end, which is the eye end, is a small aperture of about one-twentieth of an inch in diameter, the centre of which is also made to coincide very exactly with the diameter, and therefore also with the wire above-mentioned; this gives the line of sight, and the pendulum points to the degree and allowance in links to be made at each chain's length. Where, for any length, the ascent or descent is regular throughout, it will be sufficient to send a chainman forward to stand on the line, having previously marked off on your offset-staff the height of your eye from the ground. The man starts forward with this offset-staff, and holds it at the required distance, placing his hand on the above-mentioned mark, so that you may ascertain the point to which you are to direct your sight. Immediately you have done this the pendulum points to the allowance to be made at each chain's length, which your assistant carefully observes immediately the pendulum is at rest. This allowance you may as well make on the spot, by drawing the chain forward a certain distance equal to the allowance pointed out by the pendulum on the instrument. Suppose, for instance, that the allowance pointed out be six links, then for the chain to measure one chain horizontal along the inclined ground, you must lay your chain on the ground to its full length, and place the arrow at six links beyond the end of it; and this at every chain. To make this more intelligible, let the reader, as soon as he understands the use of scales, lay down an horizontal line and an inclined line, the two forming an angle of twenty degrees. To a large scale lay off five or six chains along the horizontal line, and he will find the inclined chain to measure 106 links. This drawing of the chain forward will have to be done going either up or down the side of a hill. This instrument the reader may have very cheaply manufactured, by making a tracing from the plate, pasting it on a bit of drawing-paper, getting a semicircular box made about half an inch deep with the apertures above-mentioned, and with a glass face to the box to prevent injury and also the effect of the wind on the pendulum when the instrument is in use. Messrs. Elliott now manufacture a most complete little card for this purpose.

As yet we have only spoken of chaining as regards measurement, without saying anything of the observations that have to be made as the work proceeds, consisting of notes as to where the chain intersects hedges, fences, brooks, &c., &c., on the line, and of such objects, or any others by the side of it, as we go along. These observations to objects by the side of the line are made by what is called "taking offsets." They are simply short measurements taken at right angles to the chain; the exact