helpful. All known errors have been corrected. The assistance pro­ vided by most manufacturers (or their agents) with the updating of the tables with the instrument data was greatly appreciated. Sydney, February 1996 1. M. RUEGER v Preface The book has evolved from the author's continuing teaching of the subject and from two editions of a text of the same title. The first edition was published in 1978 by the School of Surveying, Universi­ ty of New South Wales, Sydney, Australia. Like its predecessors, this totally revised third edition is designed to make the subject matter more readily available to students proceeding to degrees in Survey­ ing and related fields.