6th. He should be especially careful in the manner of keeping his field book; every thing noted in it should be clear and explanatory, so as not to admit of doubt in the event of another person having to put up or plot work from it; a neat field book denoting the careful Surveyor, as much as a dirty and untidy one is proof of the contrary.

7th. The field work should be subjected to test as soon as possible, and any errors rectified by re-observation or re-measurement whilst on the spot; if delayed for any time, the difficulty and inconvenience of returning to the spot will be so great as to prevent a fair correction being made and accuracy will be sacrificed in consequence.

8th. At the close of a day's work, measure the Chain, and note in the field book the quantity it may have stretched, so as to make allowances in any calculations that have to be made from measurements taken with it.

9th. The Surveyor should never allow himself to get into the habit of making his observations, whether angles or bearings, in a careless manner, under the impression that a small error in one observation will perhaps counterbalance itself in the next; he will find it more profitable in the end, to make ten careful observations during a day's work, than a hundred careless ones; the same remarks hold good for Chain mea

surements.

10th. No observation, memorandum, or note, should ever be recorded on slips of paper, and rejected, or be thrown aside as unimportant or useless; it is too commonly the practice to do this, but the time may come when the Surveyor would hail with delight the recovery of the remarks or calculations however roughly noted, which before he had thrown away; nothing can be too minute or too trifling to insert in the field book, whatever attracts the eye in the field, or comes within reach of the ear, should be so entered, as to be useful and intelligible to others as well as to himself at any future

moment.

Lastly. A Surveyor should always endeavour to obtain a good knowledge of his District, or the portion of country under survey, by constantly riding over it, in every direction, and thus getting a sort of bird's-eye view in his own mind, this will enable him to check any glaring omissions in the maps produced by his subordinates, and give him a great advantage in prosecuting his operations, and making the best disposition of his work. In large establishments, such as those of the Revenue Surveys now in progress, composed of large bodies of Native, East Indian as well as European Assistants, the best results may be expected from an active personal supervision in the field, and indeed without this there can be no hope of proper and systematic progress or of the quantity of work which is performed being at all satisfactory or trustworthy.

In hilly countries more especially, the eye of the Superintending Officer must be abroad to render the Topography of his maps of any value; where the Surveyor himself does not take a part in these duties, and animate his European and East Indian Assistants by his example, it will be found that they, in turn, will devolve all the laborious and irksome duties on the Native Assistants, who soon become careless and indifferent when they find themselves uncontrolled.

When once a Surveyor contents himself with ordering and directing others to do, what he never thinks of undertaking himself, he may rest assured that it never will be done well. The first principle in the life of a Surveyor should be, to make a practice of putting his own shoulder to the wheel, and then to expect and demand equal zeal from his subordinates.

At the commencement of his professional career, a Surveyor will meet with many obstacles and annoyances, and frequently find himself placed in most trying circumstances, such as will almost induce him to relinquish the task he has in hand, but he must make up his mind to this and endeavour to overcome them, and not despair of success, because threatened with apparently insuperable difficulties, the pleasure of looking

back on an accomplished task, will always be heightened by the amount of difficulty overcome, or the remembrance of peculiar obstacles successfully contended against. All beginners should take encouragement from the fact of hundreds of men having commenced their career in perfect ignorance of the various duties they may have been called on to perform, and which by dint of industry and perseverance they have finally triumphed over and completely mastered.

CHAPTER II.

ON SURVEYING BY THE CHAIN ONLY.

In making a Survey with the Chain only, we are confined to one, and the simplest geometrical figure, viz., the triangle, for of all plane geometrical figures, it is the only one of which the form cannot be altered, if the sides remain constant. That the triangle possesses this property is evident from the Theorem (Euclid 7. 1.) which proves that "Upon the same base, and on the same side of it, there cannot be two triangles that have their sides, which are terminated at one extremity of the base, equal to one another, and likewise those which are terminated in the other extremity, equal to one another."

The surface to be measured is therefore to be divided into a series of imaginary triangles; and in this division it must be borne in mind that the triangles are to be as large, with reference to the whole surface to be measured, as is consistent with the nature of the ground; for, by such an arrangement, we are acting on the important principle in all Surveying operations, (Page 237) that it is well always to work from whole to part, and rarely from part to whole.

The sides of these triangles are first measured, and as a necessary check, on this first part of the work, a straight line is in addition measured from one of the vertices to a point in or near the middle of the opposite side. This fourth line is called a tie-line, and is an efficient means of detecting errors any have been committed in the measurement of the sides of the triangle. This fourth measurement is made in accord

if

ance with a maxim which ought invariably to be acted upon in all Surveying operations, viz., that where accuracy is aimed at, the dimensions of the main lines, and the positions of the most important objects, should be ascertained or tested by at least two processes independent one of the other. Within the larger triangles, as many tie-lines and smaller triangles are to be measured as may be necessary to determine the position of all the objects embraced in the Survey. The directions of the lines forming the sides of these secondary triangles are so selected or disposed that they shall connect, and pass close by, as many objects as possible, so that the offsets to be measured from them may be as short and as few in number, as practicable.

If the sides of these secondary triangles be in any case so distant from the objects whose positions are to be determined as to require a length of offset greater than one or two chains, it then becomes advisable to construct, either on the whole or a part of the side of the triangle as a base, a smaller offset triangle with the sides so disposed that they shall either embrace, or pass very near to the objects to be measured by their intervention.

The disposition and general combination of these triangles demanding care and judgment, it is customary, previous to commencing any measurement, to walk over the ground for the purpose of obtaining a general knowledge of the surface, and of the relative positions of the most conspicuous objects. The acquisition of this knowledge depending on the coup d'œil, is much assisted by an eye-sketch drawn with rapidity, and showing some of the principal roads, streams, temples, &c.

This hand-sketch is not to be drawn to any scale, and its object is attained if it simply bear a general resemblance to a plan of the ground, as it will thereby assist the memory in the distribution of the surface into triangles.

The sides of the larger triangles are to pass as close as possible to the external boundaries to be surveyed; the triangles