AN ESSAY ON THE USE OF THE SPIRIT LEVEL, AS APPLIED TO ENGINEERING AND OTHER PURPOSES BY T. OSWALD BLACKETT, SURVEYOR, &c. NEWCASTLE UPON TYNE: PRINTED BY T. AND J. HODGSON, UNION STREET, AND SOLD BY E. CHARNLEY, BIGG MARKET; AND SIMPKIN, MARSHALL AND CO., LONDON. 1838. Physi Sci PREFACE. TA 565 THE great importance of the Art of Levelling, particularly at the the present day when public enterprize is leading to the accomplishment of the most stupendous undertakings in Railways, and other important works, will obviate the necessity of an apology for this attempt to facilitate the study of one of the most useful branches of sci ence. There has been little published on this subject, except detached fragments inconveniently arranged, and so antiquated, as to be of no utility to those who seek for practical instruction. Of these truths every one acquainted with the subject must be convinced, and that a work systematically arranged was required; I have, therefore, drawn up the present treatise, which I submit as likely to be useful to the civil and military Surveyor or Engineer, and of the greatest advantage to the junior branches of society who may be designed for these professions. |