PRACTICAL SURVEYING UNIV. OF A Text-Book FOR STUDENTS PREPARING FOR EXAMINATIONS OR FOR SURVEY-WORK IN THE COLONIES BY GEORGE WM. USILL, A.M.I.C.E. AUTHOR OF "THE STATISTICS OF THE WATER SUPPLY OF GREAT BRITAIN," CROSBY LONDON LOCKWOOD AND SON 7, STATIONERS' HALL COURT, LUDGATE HILL 1889 [All rights reserved.] PREFACE. In submitting this little work to the Public, I take the opportunity of saying a few words in explanation of my object in compiling it. My experience during several years past in delivering courses of lectures on Surveying and kindred subjects, and in preparing gentlemen for the Colonies, has shown me that, however excellent and comprehensive many existing text-books may be, they are in some points not sufficiently explicit nor in others sufficiently concise to enable the student, especially in cases of self-instruction, to grasp with readiness the subjects of which they treat. A textbook of somewhat different character seems, therefore, to be called for. In the present work I have endeavoured to make each chapter complete in itself, and to let the chapters follow in progressive order. I have also considered it better to explain the various instruments required in Surveying and their adjustment, before proceeding to describe their use and manipulation in the field. I follow then with a chapter devoted to a graphic treatment of Trigonometry as applied to Surveying; and the several succeeding chapters are intended to briefly explain the modus operandi of Theodolite Surveying, Traversing, Town Surveying, Levelling, Contouring, Settingout Curves, Office Work, and the Computation of Land Quantities. In preparing the matter here presented, I have not only drawn upon my own experience, but have consulted many of the chief works upon the subjects in question, and I desire to acknowledge my indebtedness to the authors of the works thus consulted. I have also to express my obligations to the Astronomer-Royal, to Messrs. Troughton and Simms, and to Mr. J. H. Steward, for valuable information and assistance; whilst to my former pupils, Messrs. H. S. Fearon and James Holden, I am indebted for the surveys of Wimbledon Park and Cardiff. I wish also to acknowledge the assistance I have received from Mr. John F. Curwen, in the revision of the mathematical portions of the work as they passed through the press. Subjects necessary to be known-Standards of Measure-Chains- Advantages of 100-feet Chain-Gunter's, or 66-feet Chain-Divi- sions of Gunter's Chain-Décamètre Chain-Arrows-Offset Staff- Reconnoitre-Sketch Map-Stations-Main Stations-Subsidiary Sta- tions—Testing the Chain-Test Gauge-Chain and Arrows: throwing out and doing up-Chain-men-Leader's Duties-Duty of Follower -How to use the Chain-Crossing Hedges-Hedge and Ditch- How to measure Fence-Foot-set Hedges-Offsets-Optical Square and how to use it-As to Buildings-Corners of Fields-To fix Position of an Intersection-Limit of Offsets-Pacing—Objections to Tapes for Offsets-Offset Staff-Ranging out Lines-What is Level Ground-Observing Angle of Slope-Adjusting the Allowance - Cross Staff-Optical Square-Line Ranger-Clinometer Merrett's |