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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found in a vast number of standard and expensive works, but embodying the precise Modus Operandi of the Department from unpublished and exclusive sources, appears now to be called for; and it is hoped, that in the absence of any other similar publication, which the Editors have long most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.

In the Typographical appearance of the work neither expense or trouble has been spared, and it is hoped that the Diagrams and Plates drawn on Stone, and struck off separately after the printing of the text, will be at least equal in clearness and precision to the wood cuts of an English volume. The employment of two distinct presses has of course caused infinite trouble and delay, but the art of wood cutting in Calcutta, is still almost unknown, and it was therefore hopeless to carry out the design by any other means than those adopted. In the correction of the Press the utmost pains have been taken, and although the Errata in the first few pages are more numerous than could be desired, the latter part of the work will, it is believed, be found as correct as it is possible to print such difficult matter in this country. Most of the computations have been reworked after the figures were in print, and every proof has had five or six readings.

The preparation of the work has been carried on under a press of engagements, and merely at moments of leisure after other arduous duties of the day had been attended to, which has caused the time of its publication to be very much protracted. That it contains many defects, the compilers are fully sensible of there is much which in the arrangement and the matter


they would willingly alter if in their power. They only desire to remind their readers, that the space devoted to certain subjects precluded the possibility of entering into them more fully; in some single Chapters are condensed, what might with ease be extended into a volume. It is not professed to treat of the higher branches of Geodesy, for instance, the Measurement of Base Lines, by Compensation Bars,-the Treatment of observed angles according to the Theory of minimum squares, so as to satisfy the Geometrical conditions of the figures to which they may appertain, -or all the refinements necessary to carry out an important Trigonometrical Survey, such as that now in progress in this country. The object has been to include so much merely, as may be useful and necessary for ordinary Topographical or Revenue Surveyors, and if the materials thus thrown together have the effect of maintaining a high standard of accuracy in whatever Survey operations may be undertaken, to keep pace with the refinements of the present day, and to the benefit and extension of our geographical knowledge, the labor expended in passing such a volume through the Press, will be most amply repaid.

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