III. A complete system of Surveying with only a chain, a rope, or any substitute, (invaluable to farmers having no other instruments,) is very fully developed in Part II.

IV. The various Problems in Chapter 5, of Part II, will be found to constitute a course of practical Geometry on the ground. As some of their demonstrations involve the "Theory of Transversals, etc," (a beautiful supplement to the ordinary Geometry), a carefully digested summary of its principal Theorems is here given, for the first time in English. It will be found in Appendix B.

V. In Compass Surveying, Part III, the Field work, in Chapter 3, is adapted to our American practice; some new modes of platting bearings are given in Chapter 4, and in Chapter 6, the rectangular metho of calculating contents is much simplified.

VI. The effects of the continual change in the Variation of the mag netic needle upon the surveys of old lines, the difficulties caused by it and the means of remedying them, are treated of with great minuteness of practical detail. A new table has been calculated for the time of "greatest Azimuth," those in common use being the same as the one prepared by Gummere in 1814, and consequently greatly in error now from the change of place of the North Star since that date.

VII. In Part IV, in Chapter 1, the Transit and Theodolite are explained in every point; in Chapter 2, all forms of Verniers are shewn by numerous engravings; and in Chapter 3, the Adjustments are elucidated by some novel modes of illustration.

VIII. In Part VII, will be found all the best methods of overcoming obstacles to sight and to measurement in angular Surveying.

IX. Part XI contains a very complete and systematic collection of the principal problems in the Division of Land.

X. The Methods of Surveying the Public Lands of the United States, of marking lines and corners, &c., are given in Part XII, from official documents, with great minuteness; since the subject interests so many land-owners residing in the Eastern as well as in the Western States.

XI. The Tables comprise a Traverse Table, computed for this volume,
and giving increased accuracy in one-fifteenth of the usual space; a
Table of Chords, appearing for the first time in English, and supplying
the most accurate method of platting angles; and a Table of natural
Sines and Tangents. The usual Logarithmic Tables are also given
The tables are printed on tinted paper, on the eye-saving principle of
Babbage.

XII. The great number of engraved illustrations, most of them crig-
inal, is a peculiar feature of this volume, suggested by the experience of
the author that one diagram is worth a page of print in giving clearness
and definiteness to the otherwise vague conceptions of a student.

XIII. The practical details, and hints to the young Surveyor, have
been made exceedingly full by a thorough examination of more than fifty
works on the subject, by English, French and German writers, so as to
make it certain that nothing which could be useful had been overlooked.
It would be impossible to credit each item (though this has been most
scrupulously done in the few cases in which an American writer has been
referred to), but the principal names are these: Adams, Ainslie, Baker,
Begat, Belcher, Bourgeois, Bourns, Brees, Bruff, Burr, Castle, Fran-
coeur, Frome, Galbraith, Gibson, Guy, Hogard, Jackson, Lamotte,
Lefevre, Mascheroni, Narrien, Nesbitt, Pearson, Puille, Puissant, Reg-
nault, Richard, Serret, Simms, Stevenson, Weisbach, Williams.

Should any important error, either of printer or author, be discovered.
(as is very possible in a work of so much detail, despite the great care
used) the writer would be much obliged by its prompt communication.

The present volume will be followed by another on LEVELLING AND
HIGHER SURVEYING: embracing Levelling (with Spirit-Level, Theodo-
lite, Barometer, etc.); its applications in Topography or Hill-drawing,
in Mining Surveys, etc.; the Sextant, and other reflecting instruments;
Maritime Surveying; and Geodesy, with its practical Astronomy.

[A full Analytical Table of Contents is given at the end of the volume.]

PART I. GENERAL PRINCIPLES AND OPERATIONS.

CHAPT. 1. DEFINITIONS AND METHODS..

CHAPT. 2. MAKING THE MEASUREMENTS.

CHAPT. 3. DRAWING THE MAP

CHAPT. 4. CALCULATING THE CONTENT

PART II. CHAIN SURVEYING.

PART III.

CHAPT. 1. ANGULAR SURVEYING IN GENERAL

CHAPT. 2. THE COMPASS..

CHAPT. 3. THE FIELD-WORK

CHAPT. 4. PLATTING THE SURVEY

CHAPT. 5. LATITUDES AND DEPARTURES

CHAPT. 6. CALCULATING THE CONTENT

CHAPT. 7. MAGNETIC VARIATION

CHAPT. 4. SURVEYING BY THESE METHODS COMBINED.
CHAPT. 5. OBSTACLES TO MEASUREMENT......

COMPASS SURVEYING.

82

96

122

127

138

157

169

180

189

CHAPT. 8. CHANGES IN THE VARIATION.

PART IV. TRANSIT AND THEODOLITE SURVEYING.

PART VI. TRILINEAR SURVEYING......

PART VII. OBSTACLES IN ANGULAR SURVEYING.

PART XI. LAYING OUT AND DIVIDING UP LAND.

APPENDIX B-DEMONSTRATIONS OF PROBLEMS, &c.

387

APPENDIX C-INTRODUCTION TO LEVELLING

409

ANALYTICAL TABLE OF CONTENTS....

415

TO TEACHERS AND STUDENTS.

As it is desirable to obtain, at the earliest possible period, a sufficient knowledge of the genera

principles of Surveying to commence its practice, the Student at his first reading may omit the

vortions indicated below, and take them up subsequently in connection with his review of his studies.

The same omissions may be made by Teachers whose classes have only a short time for this study.

In PART I, omit only Articles (46), (47), (48), (51), (72), (94), (85).

In PART II, omit, in Chapter IV, (127), (128), (129), (130); and in Chapter V, learn at first

ander each Problem, only one or two of the simpler methods.

In PART III, omit only (225), (226), 232), (233), (244), (251), (280), (297), (322)

Then pass over PART IV; and in PART V, take only (379), (380); and (391) to (395).

Then pass over PART VI; and go to PART VII, (if the student has studied Trigonometry

and omit (423); (431) to (438); and all of Chapter IV, except (439) and (440).

PART VIII may be passed over; and PARTS IX and X may be taken in full.

in PART XI, take all of Chapter I; and in Chapters II and III, take only the simpler con

ructions, not omitting, however, (517), (518) and (538).

In PART XII, take (560), (561), (565), (566).

Appendix C, on LEVELLING, may conclude this abridged course,

LAND-SURVEYING

PART I.

GENERAL PRINCIPLES

AND

FUNDAMENTAL OPERATIONS.

CHAPTER I.

DEFINITIONS AND METHODS.

(1) SURVEYING is the art of making such measurements as will determine the relative positions of any points on the surface of the earth; so that a Map of any portion of that surface may be drawn, and its Content calculated.

(2) The position of a point is said to be determined, when it is known how far that point is from one or more given points, and in what direction there-from; or how far it is in front of them or behind them, and how far to their right or to their left, &c; so that the place of the first point, if lost, could be again found by repeating these measurements in the contrary direction.

The "points" which are to be determined in Surveying, are not the mathematical points treated of in Geometry; but the corners of fences, boundary stones, trees, and the like, which are mere points in comparison with the extensive surfaces and areas which they are the means of determining. In strictness, their centres should be regarded as the points alluded to.