Punctuation has been standardised, and possible typographical errors have been changed.
Archaic, variable and inconsistent spelling and hyphenation havebeen preserved.
SURVEYING AND LEVELLING
INSTRUMENTS
FOR CONSTRUCTION, QUALITIES, SELECTION, PRESERVATION,ADJUSTMENTS, AND USES; WITH OTHER APPARATUS AND APPLIANCESUSED BY CIVIL ENGINEERS AND SURVEYORS IN THE FIELD.
BY
WILLIAM FORD STANLEY
OPTICIAN, MANUFACTURER OF SURVEYING AND DRAWING INSTRUMENTS,
AUTHOR OF A TREATISE ON DRAWING INSTRUMENTS,PROPERTIES AND MOTIONS OF FLUIDS, NEBULAR THEORY, ETC.
FOURTH EDITION
Revised by H. T. TALLACK.
LONDON: E. & F. N. SPON, LTD., 57, HAYMARKET, S.W.
NEW YORK: 123, LIBERTY STREET
AND OF
W. F. STANLEY & CO., LIMITED
286, High Holborn, London, W.C.
1914
Notes were taken for many years before the production ofthis work of queries that came before the author for replyrelative to functional parts of surveying instruments. Thesebore most frequently reference to optical and magneticsubjects, and to the qualities and action of spirit level tubes,also occasionally to graduation and the qualities of clamp andtangent motions. It was therefore thought that it would beuseful to give notes upon these subjects in detail as far aspossible in the early chapters. As the work proceeded it wasfound that this plan saved much space in avoiding thenecessity for separate descriptions when parts of complexinstruments were afterwards described.
To show the state of the art and render the work useful,it was necessary that the structure of surveying instrumentsshould be given with sufficient detail to be worked out by theskilful manufacturer. Beyond this it was thought to be mostimportant that the professional man, who must have limitedexperience of the qualities of workmanship, should be suppliedwith as many simple tests as possible for assuring the qualitiesof the instruments he might purchase or use, with details alsoof their adjustments. This matter is therefore carried intodetail for one instrument at least of each class, as very little[iv]general information is to be found on the subject in ourliterature. In fact, large groups of instruments in extensiveuse, such as those used for mining surveying, and subtensemeasuring instruments, have remained heretofore nearly undescribedin our language.
The technical principles followed in working out detailsin these pages are given by illustrations of such parts ofimportant instruments as present any difficulty of observationfrom an exterior view of the engraving of the entire instrument.The plans of construction in general use are selectedfor illustration. Certain constructions that are liable to failureare pointed out. Many recent improvements in instruments