ENGINEER'S, MINING SURVEYOR'S FIELD-BOOK. BY W. DAVIS HASKOLL, CIVIL ENGINEER. SECOND EDITION, MUCH ENLARGED. CONSISTING OF A SERIES OF TABLES, WITH RULES, TRAVERSE SURVEYING AND PLOTTING THE WORK WITH MINUTE ACCURACY BY MEANS OF STRAIGHT EDGE AND SET SQUARE ONLY; LEVELLING WITH THE THEODOLITE, CASTING OUT AND REDUCING LEVELS TO DATUM, SETTING OUT CURVES WITH THE THEODOLITE BY TANGENTIAL ANGLES AND MULTIPLES WITH RIGHT AND LEFT-HAND READINGS OF THE INSTRUMENT; SETTING OUT CURVES WITHOUT THEODOLITE ON THE SYSTEM OF TANGENTIAL ANGLES BY SETS OF EARTHWORK TABLES TO 80 FEET DEEP LONDON: LOCKWOOD & CO., 7 STATIONERS'-HALL COURT. HARVARD UNIVERSITY "CHOOL OF ENCH JUN 20 1917 TRANSFERRED TO MANFÄKT COLLEGE LIEKARY 345.18 LONDON PRINTED BY SPOTTISWOODE AND CO. NEW-STREET SQUARE SINCE the First Edition of the 'Field Book,' the author has found, through conversation with numerous friends, that it would be advisable to enter more into detail as to the application of the Tables. He has therefore given, in the Introduction to this Second Edition, an explanation of the system of levelling with the theodolite, by which the student may perceive how rapidly a network of trial levels may be obtained over a very extensive area through a hilly country; and also of the system of traverse surveying and plotting, more particularly as applicable to the working surveys required through thickly populated districts, where great accuracy in the plans is necessary. For those who object to the theodolite, a set of tables has been given for setting out curves by numerous offsets from one tangent. The author has besides added, in this Second Edition, Earthwork Tables for every 6 inches up to 80 feet deep; and a Table of Gradients, which will be found to reduce very considerably the labour of preparing working sections. A 2 Ir is not unworthy of remark that, whilst every branch of engineering, with two exceptions, has, during the last thirty years, been progressing with 'giant strides,' the exceptions, land surveying and levelling, remain exactly where they were; this, of course, is the general rule only: there are exceptions, no doubt, numerous. Taking into consideration the great advantages of the present day, in the shape of ordnance maps, tithe plans, improved instruments, and the gradients and curves which we may now adopt, it is doubtful whether, generally speaking, surveyors know as well now how to pick out a line of railway as the professional man of a quarter of a century ago. This was about the only reproof made against the engineer by Lord Redesdale in his late 'raid' on railway people generally. His lordship observed that railway plans were not sufficiently studied; the observation is not a whit more flattering to the writer than to his brother professionals, but he submits that it is true. It would, of course, be unfair to apply this observation to those cases where a professional man is sent down at the very last moment, when there is scarcely time to prepare any plans and sections whatever, afte merely giving a glance at a country, where he can very often barely se a mile ahead. The condition now more particularly referred to, i where the engineering surveyor is engaged in actual exploring or tria levelling for the selection of a line of railway at home or abroad, an as to the most expeditious method of obtaining sufficient levels to ensur the best passes, the most favourable starting-points when we are a liberty to select, and the best points or thereabouts along the line so as to avoid heavy works. These circumstances necessitate getting over ‹ wide expanse of ground in a short time, and this can be done only by adopting suitable means. The 'good old times' have passed away, when we laid out railways through flat and undulating countries; with very few exceptions, these territories are all fully occupied, and the engineering surveyor, in projecting lines of railways at the present time, must make up his mind to wind along hills and over mountains. Not only the ground is broken in every direction by chains of lofty hills, but out of these run numerous spurs and valleys which require close study before anything like a good line can be laid out amongst them, even after a particular general route of country has been determined on as the best, purely from an engineering point of view. In such districts as are now referred to, the hills very commonly rise and fall 50 and 100 feet within very short distances, such as 100 or 150 yards; not only is it necessary to have levels over such ground, so as to avoid as much as possible very heavy works, but the pass has often, and indeed most generally, to be kept in view, whether it be very high or very low ground; and not only the ground rises and falls in numerous places at the rate above mentioned, for distances of 100 and 150 yards, but often also at the same rate for ten times such distances. Again, before the general route above referred to can be determined upon, the country for a mile or two right and left, and often much more, requires examination, not merely by the eye, which in really hilly countries is very likely to deceive, but by some rapid instrumental exploration; and it is only when this has been done that the best line generally can be discovered. The work more particularly referred to now, is railway work at home, where we have often a severe parliamentary ordeal to go through; this we observe advisedly, for unless we have opposition, it matters very little, except as regards expense, what kind of a line is brought forward. Notwithstanding all these difficulties, however, which have sprung up naturally, and simply from our having to project our works under circumstances generally so very different to those of twenty and thirty years ago, we adhere, with only a few exceptions, to exactly the same instruments, and the same mode of using them as we did then. The reserve, however, of a few exceptions has been made, because there are engineering surveyors who have adopted a totally different method of going to work, and mostly they are well and profitably employed; but in subjects of this kind we cannot refer to exceptions, and we can only deal with the general state of things as we meet with them. The only instrument still generally employed for getting explore levels, even over the most hilly country, is only and simply the level in its ordinary form; and, however expert the observer may be, he will not get over a hundred feet rise in much less than six observations: with the theodolite this is done at one sight, that is, with five-sixths less trouble and time. The ordinary mode of using the level for trial levelling, is to begin at some particular point, and to wind up and down with instrument and staff along the sidelying ground proposed to be adopted, and so get a few levels right and left, these being referred to in the level book, and on a plan by letters or numbers. One trial line having been got over, another line is tried in the same manner; but, from the nature of the instrument in its simple form, the work is slow, and in hilly countries |