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PREFACE.

IN the United Kingdom, and with Ordnance Maps to various scales, and more or less corrected to date, always at hand, the surveyor seldom, if ever requires to put into practice a knowledge of high class, or Geodetic Surveying. The result is, that diplomas are granted to students who possess but a very limited knowledge of this class of work.

In the principal Colonies, however, these conditions do not obtain, and their governments, not being satisfied with the limited acquirements of many English surveyors, insist on a local training, or apprenticeship and the possession of one of their own diplomas. This restriction has, in many cases, proved somewhat arbitrary.

About three years ago, a number of gentlemen interested in this question, and in the improvement of the standard of qualifications for English diplomas as Surveyors, met at the Surveyors' Institution by kind permission of the Secretary, and formed a committee to consider what steps might best be taken to secure a better position for the English student who might wish to seek employment in one of our Colonies.

The Council of the Surveyors' Institution was approached, and their Secretary, Mr. Julian Rogers, informed the committee that their members were prepared to look favourably on any efforts made in the direction indicated.

It was arranged that the committee should prepare, and submit a Text-Book, which the Council agreed to adopt, if satisfied with the

same.

The present Treatise on Surveying is the result, and in order to

meet the requirements of a body of students who may seldom, if ever, practise the art of Geodetic Surveying, but to whom a knowledge of the practices of ordinary surveying is a necessity, the work has been divided into two Parts, so that problems requiring Geodetic treatment, and Astronomical determinations, as well as the manner of Conducting Marine, Route, and other special surveys, are discussed in the Second Part.

The Authors of this work make no general claim to originality, since most of the information given is to be found in some one or other of the many existing treatises on surveying; but, so far as they know, no one book contains in a practical form the information now offered to the student.

In addition to the various methods of surveying limited areas, as usually practised, every effort has been made to point out clearly, the degree of accuracy which can readily be obtained with the appliances available, and which is essential with regard to the purpose for which the survey is undertaken.

Further, the effects of different sources of error (avoidable, or otherwise) on the ultimate accuracy of the work, have been discussed, so that the surveyor may decide how advisedly to apportion the time and care. that he should bestow on the various processes of his work. Some space has also been devoted to the considerations which affect the distribution of residual errors, in a simple yet systematic manner.

The Authors beg to offer the above remarks as their justification for submitting this work to the verdict of public opinion, and whilst making no claim to having compiled a complete treatise on so large a subject as surveying, still it is hoped that all the information necessary to enable a student to acquire the knowledge required of a qualified surveyor is to be found in it.

The following is a list of the Contributors; and it is deeply to be regretted that the sections written by Mr. LEANE (who died at sea when on his return from Africa) and by Major-General WOODTHORPF. C.B.

(appointed Surveyor-General of India just before his death) have had to be produced without the advantage to the Editor of being able to submit proofs for their revision:

REGINALD E. MIDDLETON, M. Inst. C.E., M. Inst. Mech. E., F.S.I., Fellow of the Sanitary Institute.

Formerly Instructor in Surveying at the Central Institute of the City and Guilds of London, &c.

OSBERT CHADWICK, M. Inst. C.E., M. Inst. Mech. E., Mem. San. Inst.
A Consulting Engineer to the Crown Agents for the Colonies.

J. DU T. BOGLE, Colonel (late R.E.).

Formerly Instructor in Surveying, S.M.E., Chatham.

G. H. LEANE, F.S.I.

Examiner in Surveying to the Surveyors' Institution, the Royal Agricultural Society, &c. (since deceased).

MAJOR-GENERAL WOODTHORPE, C.B. (late R.E.).

Appointed Surveyor-General of India just before his death.

The thanks of the Authors are due to Mr. M. T. ORMSBY, Demonstrator in Surveying at University College, Gower Street, London, for assisting in the editing of the work, and in the preparation of drawings, tables, &c. It is believed that all matter taken from other sources has been acknowledged in the text.

PREFACE TO THE SECOND EDITION.

IN the present Edition it will be found that the clerical errors which existed in the First have been corrected, and a few Appendices have been added dealing with some omissions which had inadvertently occurred and escaped the notice of the compilers.

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