In the present Edition, which represents forty-seven years of experience of the author's life devoted to the details of the subject, it is hoped that some permanent improvements in surveying instruments may be shown, and that many new designs now first described, founded upon this experience, may merit trial.
The author is pleased to acknowledge the zealous aid his working manager and at present co-director, Mr. H. T. Tallack, has given in perfecting this work to bring it to its present state.
W. F. S.
Great Turnstile, 1901.
PREFACE TO FOURTH EDITION.
Since the publication of the Third Edition of this work, the author has been taken from us, and it has fallen to my lot to revise it and bring it up to the present time. This work I have approached with the greatest diffidence, having to follow one who had such profound knowledge of the subject, and I have earnestly endeavoured, as closely as possible, to act as I think he would have done had he been alive, and having enjoyed over twenty years of the happiest and closest business relations with him—actively co-operating in bringing many of the instruments to their present state, I venture to hope that I have to some extent carried out what his wishes would have been.
I have carefully read over and corrected the whole work, and the additions to it are only in the nature of bringing it up to date.