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least a five if possible. When we come to the subject of Chain Surveying, we shall have an opportunity of saying a few words more on this subject.
The "field-book” is a register in which all observations and notes connected with a survey are duly made, and we might almost say that the number of forms for keeping this field-book is as numerous as the number of surveyors; the great desiderata, however, are simplicity, and easy reference throughout its pages; it ought to be so very intelligible, that any person acquainted with surveying can make the plot of the survey from end to end without any uncertainty or difficulty, and although this may at first appear difficult with three or four hundred pages of notes, a good system makes it perfectly simple and easy. The form of field-book given in these pages is one we have been accustomed to use for upwards of twenty years, on every description of survey, and we have never seen occasion to alter it; we have therefore reason to believe it one of the very best-it is convenient in the field, intelligible in the office, and of so easy a reference, that there is no difficulty in plotting a survey from it years even after such survey has been made. This field-book is about four and a-half inches wide, seven or eight long, and opening lengthways, and should be paged from end to end. Down the centre of each page, length ways, a column about half an inch wide should be ruled for entering the chainage, the offsets being registered right and left of the said lines as they occur.
With the illustration of this field-book, given with Figure 1, it is hoped that a few words will suffice to make it intelligible. For easier and more accurate reference, the chain lines are all numbered, as well as the pages, as L. 1, meaning Line No. 1. The reason for this is, that, in each long double page, there may sometimes be half-a-dozen chain lines, when there are not many offsets to take on them; and it may so happen that two stations,
l on different lines, may be registered by the same figures; referring, therefore, to the number of the page would not be sufficient, and reference must also be made to the number of the line on which the station occurs. Let the reader now refer to L. 1 in the field-book, and to the plan shown at Figure 1, where L. 1 is shown by the letters A B; and note particularly that, in this field-book, the pages all commence at the bottom of the page, by which means you read onwards in the same manner you are chaining. After taking a cursory view of the ground to be surveyed, this line was adopted as the base of operations. We commenced at A, by the trunk of an old oak tree, and there being a tall chimney about a mile off, in the
direction required, we chained for it instead of sending on a pole. Nothing occurs until we come to the third chain, on which, at 40 links, a station is made for running a line to take the curved fence on the left-hand side. The follower having two arrows in hand, this station is registered as 240. On the fourth chain we intersect a fence, the brow of the ditch at 340, and the quick at 348; the direction at which the chain
passes by these being sketched in, there is no further note to make until the first ten arrows are expended, which is duly registered. The next observation to make is the intersection of ditch and fence at 1395 and 1405 ; we have now some offsets to take, and to sketch in the relative position of the fence with the chain line. To do this stand on your chain line, facing your fore object, and sketch in the fence as it appears receding from or approaching the chain, and never sketch in more than three or four chains at a time, and as you proceed, or you will find that very often
you will be obliged to have recourse to your Indianrubber to efface that which on close inspection proves to be different to what it appeared seven or eight chains off; look out carefully for the chainage, from which a perpendicular will fall to meet intersections of fences. The habit of accurately sketching in the position and appearance of objects, as they occur along the side of the line, is very valuable as affording material assistance in laying down the plot with the help of the registered lengths of chainage and offsets; it is only to be acquired by practice. No further observations are now required as to this line until we reach the end of it at 5060, from which point it is observed that two lines can be struck out right and left for taking up the fences on both sides. We now come to line 2. This commences with the following sign , which means turn to the right from the last line; the starting point of this second line is 5060 on the last line, and the last station of that line; it is therefore entered as From 5060 last ;' now observe that this sign and the figures of the station give the starting point and the direction taken, this information being for afterwards plotting the work ; were the sign left out we should have to trust to memory as to whether we turned to the right or the left. Having chained this line, and taken the offsets, we come to the end of it at 2300 as a station ; this point is fixed upon because, standing on the chain, we see that we shall intersect from it line 1 at station 2845, left for this particular purpose, and continuing the straight line on through this station, the end of line 3 at chainage 3500 is a fixed point; its direction being determined by the starting point and the station it passes
through ; and this direction has been so fixed because it gives opportunity within good offset distance of picking up the fencing on the right and left of it. Similar remarks are made at its commencement as for the last line ; still turn to the right, and from the last station. Had it been any other station on that line it would have been from station so and so “last line."
As regards the fourth line, we have only given the commencement of it as 4, meaning turn to the left, instead of to the right as heretofore. Let us now suppose that we are beginning another line from A, but instead of going in the direction A B, that we are chaining to the right, then the sign will be L. A few words more will conclude this tedious, but very necessary explanation to the reader who is endeavouring to acquire the art of land surveying unassisted. In chaining along a road always chain in the road itself instead of in the fields by the side of it ; in the latter case you would have to offset to the one fence by crossing over the other, which is always very inconvenient; you have besides no opportunity of observing many little details which become concealed from view; such as waste by the roadside, gates, pools, bends, and breaks in the opposite fence, all of which should be shown on a good survey, particularly if the plot is to be to anything like a large scale ; always offset also both sides of a brook; buildings require particular care with regard to offsets; where in an ordinary survey these are in numerous detached blocks, it is by no means a bad plan, after having surveyed the fences immediately bounding each block of buildings, and one or two of the principal buildings also, to plot what you have actually surveyed of these, and make a tracing of the work ; then at the first convenient opportunity, with a small pocket-scale and a tape, fill in the details on the spot on the tracing ; remarkably accurate work may be thus produced and very easily, for the slightest omission or error as to the shape of the buildings will strike the eye when the work is thus examined on the ground.
A wall very often crosses a chain line, and of course totally impedes the view ; it becomes necessary to find on the other side of the wall the exact spot where the line crosses; by means of a plumb-line we can transfer this spot, first to the top of the wall, and then dropping the line to the other side obtain what we require.
We have now made every observation we can think of on this subject, and strongly recommend the reader to practise all this until he finds himself familiar with this portion of the work ; then, and not till then, it will be time for him to study the laying
out of a survey, by chain alone, or with the additional help of instruments, for which he will find instructions in the following pages.
Supposing the advice above given to be followed out, the next thing the reader will require will be the means of laying down his straight lines, bis distances, and offsets on paper. To do this a straight-edge, a scale, needle-point, and pencil are required.
A straight-edge is a long flat rule, the sides of which are as perfectly straight as it is possible to make them. This instrument is required to lay down the chain lines on paper, and since we are as careful as possible on the ground to keep this chain line straight, it is equally requisite to do so on paper. Land surveys are most usually plotted to a scale of three, four, five, or six chains to one inch; that is to say, that one inch on paper represents one or the other of those numbers of chains on the ground. Take five chains, for instance; a chain being equal to sixty-six feet, and there being five chains to the inch, the latter will represent three hundred and thirty feet; one foot, there. fore, will be represented on paper by the 330th part of one inch. The reader will now perceive the importance of a straight-edge in laying down a long chain line on paper, perhaps two or three miles, and therefore, also, the importance of the instrument with which it is to be done; and we must request of him to understand that there is nothing fastidious about the caution here given, as he will find to his cost when neglected; on the other hand, we must also request of him not to be over cautious in carrying this advice into practice, or he will positively waste much valuable time in endeavouring to obtain that which has no practical results. The following circumstance will illustrate how easy it is to fall into either extreme. Many years ago the writer was assistant to a gentleman who was engaged on a very extensive survey on which one base line measured upwards of seven miles ; a straight-edge (?) was purposely made for laying down this base, which was on mounted paper, and strained on a large board. When we came to fill in the survey, a great number of lines were run from, to or through this base, and on plotting the work we were very much annoyed and surprised, for great pains had been taken, to find that many of these lines plotted too short or too long; many of them were chained over again without finding any defects to account for the cause of our annoyance.
At last the guilty one was suspected ; a long piece of fine strong silk was procured, slightly waxed, and strained from end to end of the base, which was then discovered to be in many places as much as ten and fifteen links out of the straight line, and accounted for apparent errors in the field-work ; on a
mathematical examination of the straight-edge, it was found to be no straight-edge at all, and a great deal of work had to be done over again ; the rule was sent to a first-rate instrument maker to set right, and came back a straight-edge. Unfortunately our mishap made us over fastidious, and a very great deal of time was wasted in straightening that which was not straight in fancy only. To ascertain the correctness of a straight-edge,
two or three of them are required; two of these should be placed edge to edge, and slided along each other, whilst held between the eye and the light; if the edges exclude the light in some places, and admit it at others, then the edges are not straight, and require correcting; but they may happen to be equally curved, when, although they would fit close, still they would not be straight; then try the other side of the edge, or apply the side of a third one, and if all now be satisfactory, it may be said that they are straight, and should be prized accordingly. But even with a straight-edge it is not so easy as at first sight appears, to draw a perfectly straight line ; for instance, in joining two distant points together by means of a straight line, the edge of the rule has to be placed so as to just pass by the side of the two points; the pencil or pen must then be carried from point to point, close along the straight-edge during the whole of its transit, for if it leave the side here and there, then the line is not straight, and even the inclination of the pencil or pen will do this, you must therefore be careful to hold the pencil perfectly steady the whole way; having drawn the line, you may test it by turning the straight-edge end for end.
Chain scales are made of ivory or boxwood, usually six or twelve inches long. The principal divisions are so many to the inch, according to the scale adopted, and are numbered both ways along the side of the scale; these are subdivided into parts
ten links each, which in plotting are subdivided by the eye ; when, therefore, one of these is laid along a chain line on paper, the chainage or the different measurements are easily pricked off with a needle-point; these distances being marked along the chain line as they occur, the intersections of fences are laid down, and the offsets plotted right and left at right angles, by means of short two-inch scales, which are called offset scales. An examination of a chain scale bought at a maker's, will easily explain this; a beginner had better begin plotting his work to a large scale, that is, two or three chains to one inch, and always remember that the smaller the scale the more carefully it should be plotted, as in this case, apparently a very small error would be a considerable distance on the ground.
In a scale of 3 chains to the inch, every inch will be divided