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THE TWELFTH EDITION.

THE demand which has carried this now standard work through eleven editions is a sufficient index of the high esteem in which it is held, and renders it unnecessary for the Publishers to do more than announce the Twelfth Edition of NESBIT'S PRACTICAL LANDSURVEYING. The Appendix has been re-written, and in it is included the General Inclosure Act of 1845, which contains the statutory provisions for the extension, improvement, division, &c., of commons and waste lands, and the required formula for the surveyor and valuer. To this Act, which is given in full, is appended a list of the Acts, passed subsequently, relative to inclosures.

ADVERTISEMENT

TO

THE ELEVENTH EDITION.

THE thorough revisal and enlargement of NESBIT'S PRACTICAL LANDSURVEYING cannot fail to continue for it the very prominent position which it has long held as a standard work. The sale of TEN LARGE EDITIONS, and the demand for the present one, is a very gratifying testimony of the patronage it has hitherto merited of land-surveyors, civil engineers, masters of seminaries, and the general public.

The subdivision of the work into Ten Parts, as in the last edition, has been continued. The First Part is elementary, and contains definitions, with a few select problems and theorems. The Second gives a description of the chain, offset-staff, compass, &c., with directions for their use. The Third and Fourth embrace the mensuration of single fields, the former with the common cross-staff and chain, the latter with the chain only. Part IV. also teaches how to survey hilly and uneven ground. The surface of the earth consists of a series of hypotenusal planes joined by curved lines, and before the dimensions of these can be plotted on to a plan, they have to be reduced to base-measure or that of a common plane; and this part gives various methods of doing so by the chain, quadrant-level, and theodolite. The Fifth, Sixth, and Seventh teach how to survey large estates, apportion land, plot, finish, transfer and reduce plans. Part VI. belongs to the higher branch of land-surveying, and is divided into four sections, the first of which is elementary, the second practical; the third gives general directions for field operations, and the fourth the reduction of customary to statute measure. Part VII. includes the surveying of farm-buildings, cities, towns, villages, and lands for building purposes. The Eighth and Ninth teach the elements of trigonometry, and their application by examples. Railway

Surveying follows, and includes illustrated general directions for taking a preliminary survey of a projected railway. The Tenth includes Railway Engineering under seven sections, viz. :—

Section I. treats of levels and levelling, including trial, check, and cross levels; check levelling; correction for curvature and refraction.

Section II. contains a Parliamentary survey, with plan and section; the method of keeping the level-book and of plotting the sections; also the method of laying out gradients, &c.

Section III. shows the general principles and practice of laying out railway curves, including compound, serpentine, and deviation examples, with the necessary constructions and formulas required.

Section IV. embraces railway earthworks, and gives formulas for setting out the width of the ground, for finding the areas of the railway estate, together with auxiliary tables for finding the contents of sectional areas.

Section V. gives the methods of setting out the ground for tunnels and tunnelling, including tables of dimensions.

Section VI. is on viaducts, aqueducts, oblique railway bridges, and includes examples with dimensions.

Section VII. comprises the survey and applications of rules for the superelevation of the outside rails at railway curves.

The following is a brief summary of the principal additions and alterations made to the present edition.

Part II.-Two new articles have been written for this Part: the one on the variation of the needle of the compass; and the other, directions for correcting the compass so as to find out the true meridian.

Parts III and IV.-In these two Parts one proposition (page 85) has been corrected, and two new ones, with a diagram, added, in order to supply the necessary instruction required in ranging and measuring lines in surveys with the chain when sight is obstructed. The methods of measuring hilly ground have been re-written; so have the articles under a Quadrant, a brief description of several additional instruments of this kind being given. General directions for surveys on the vertical plane have likewise been added in Part III.

Parts V. and VI.-Very many corrections have been made in these two divisions, paragraphs out of date suppressed, and new ones written to supply their places. General directions for eight additional surveys have been added to the latter (Part VI.), while the

statutory matter which it contained in previous editions has been transferred to the end of the work in the form of an Appendix. The two first surveys are on the horizontal plane, and embrace lands intersected by a railway. The remaining six include surveys of rivers, tidal, mountainous, and intermediate; canals, embankments, lands reclaimed from the sea, &c. They are principally on the vertical plane, and form together a large section, viz., Section III.

Part VII.-General directions for surveying and designing mansions, farm homesteads, stackyards, &c., have been added to this Part; other portions of it have been re-written.

Part VIII. has been divided into five Sections. Sect. I. consists of definitions and corollaries. Sect. II. treats of the species, constructions, ratios, resolution and solution, of triangles. Sect. III. gives the trigonometrical solution of plane triangles, right-angled, and oblique. Sect. IV. the measurement of angles, with an illustrated description of the theodolite. Sect. V. is on the trigonometrical survey of heights and distances. The first two sections have been added to this edition of the work. They have been written expressly to illustrate, by means of the several diagrams annexed, the elementary principles and practice of trigonometrical surveying: it is hoped they will prove not only instrumental in facilitating the education of private students, but also in promoting that of articled pupils in field operations with the theodolite, and in the office work of plotting the bearings. Three of the cases in Sect. III. have been re-written, and numerous corrections made in this and the remaining two sections of this Part.

Part IX. embraces examples of trigonometrical surveying; it has been divided into seven Sections. Sect. I. contains rules for finding the areas of triangles by logarithms. Sect. II. To survey a wood. Sect. III. To survey a wood or river. Sect. IV. gives the practice of taking bearings by two stations. Sect. V. To survey a town or city. Sect. VI. To range lines and take bearings in extensive surveys. Sect. VII. To survey with the circumferentor. Of these, Sect. VI. has been written for the present edition, and also the Introduction containing the new subdivision of this Part.

The section under Railway Surveying has been re-written in the form of illustrated general directions for taking a preliminary survey of a portion of a projected railway. In the previous edition the illustration or plan (p. 387), and the subject-matter of the section generally, was in Part IX. under a different heading; but as