PREFACE.

It must have been apparent to the numerous Officers of the Army as well as to the various other persons appointed to the Revenue Surveys in India, that scarcely one of the many English works on Geodesy extant, touch on, or afford any practical insight into, the system of Survey as carried on, and as peculiarly applicable to this country. Valuable and of high order as many of these works are, and of great importance as fixing the leading and fundamental principles of the profession, they are destitute of the most essential parts of an Indian Surveyor's duty, and of the most useful details, for adapting such principles to the nature of the country with which he has to contend.

A Surveyor of even some experience, when placed in situations of difficulty and responsibility so common in the almost boundless fields still left unexplored in this vast country, with no competent adviser at hand, and far removed from all chances of assistance, may, and often does feel greatly at a loss; the want of

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some such work therefore, as the present, forming a concise Manual, adapted to the peculiar requirements of this country, and condensing into a small space, not only what alone can be found in a vast number of standard and expensive works, but embodying the precise Modus Operandi of the Department from unpublished and exclusive sources, appears now to be called for; and it is hoped, that in the absence of any other similar publication, which the Editors have long most anxiously looked for, from abler hands, the present attempt may not be altogether out of place.

The great extension of Surveys in India of late years, and the annexure of another large Province to the British Dominions, giving rise to the immediate necessity for a Survey and Assessment, has opened a wide field for the practical employment of Surveyors of all descriptions, both European and Native. In a Department therefore which demands a certain amount of qualification (the test for which will be found in the Appendix) it is highly desirable that previous study and fitness should form the pretensions of persons enlisting in its service. The establishment likewise of a Civil Engineering College at Roorkee, in the North Western Provinces, by His Honor the Lieutenant Governor, for the training of youths of this country, as well as of European Non-Commissioned

Officers and Privates of the Army, in the several branches of practical science, has given an additional impetus to the undertaking, and the compilation now offered to the public has been prepared with these views, as well as for practical men generally.

The arrangement of the work is consequently in the first two parts elementary, the materials for which have, of necessity, been for the most part extracted from various Authorities, chiefly from the well-known and most useful works of Mr. Simms, the Civil Engineer, and late Consulting Engineer to the Government of India, "On Mathematical Instruments" and "On Levelling". From Heather's "Treatise on Mathematical Instruments", "Jackson's" and "Frome's Surveying," " Adam's Geographical Essays," &c. &c., full extracts have been also made, and the acknowledgments of the Compilers are here duly recorded for the same, as well as to those authors from whose works extracts have been made as quoted in the Text. In the remaining Parts of the Book, it has been the aim, to render the information generally useful, not only to the Professional Surveyor, but to the Traveller and the Explorer of neighbouring countries, the Quarter Master General's Department, and for Revenue Officers, and Civil Authorities of Districts, where professional assis

tance cannot be obtained, and every Collector must be his own Surveyor.

Through the liberal and kind assistance of Lieut. Colonel Waugh, Surveyor General of India, in placing the records of his office at their disposal, the Editors have enjoyed great advantages, of which they have not failed to avail themselves to the fullest extent, for this as well as for much valuable advice, their thanks are eminently due, and most cordially offered.

In Parts III. and V. the Compilers have been very largely assisted by Babu Radhanath Sickdhar, the distinguished head of the Computing Department of the Great Trigonometrical Survey of India, gentleman whose intimate acquaintance with the rigorous forms and mode of procedure adopted on the Great Trigonometrical Survey of India, and great acquirements and knowledge of scientific subjects generally, render his aid particularly valuable. The Chapters 15 and 17 up to 21, inclusive, and 26 of Part III. and the whole of Part V. are entirely his own, and it would be difficult for the Compilers to express with sufficient force, the obligations they thus feel under to him, not only for the portion of the work which they desire thus publicly to acknowledge, but for the advice so generally afforded on all subjects connected with his own department.