A TREATISE ON THE PRINCIPAL MATHEMATICAL INSTRUMENTS, EMPLOYED IN SURVEYING, LEVELLING AND ASTRONOMY, &c. &c. ASSISTANT AT THE ROYAL OBSERVATORY, GREENWICH, AND FORMERLY LONDON: PRINTED BY T. BENSLEY, CRANE COURT, AND SOLD, FOR THE AUTHOR, BY MESSRS. TROUGHTON AND SIMMS, 136, FLEET STREET. SION COLLEGE LIBRARY. SOLD BY ORDER OF THE PRESIDENT AND GOVERNORS 1938. Entered at Stationers' Hall. Hodgson 7-739 98627 PREFACE. THE want of a work containing a concise and popular description of the principal Instruments used in Practical Astronomy and Surveying has long been felt, as the requisite information with respect to such instruments can only be obtained by consulting various expensive publications, which are not within the reach of many to whom such information is highly interesting and important. It was the original object of the writer of this little tract, to place at the disposal of the young surveyor a description of the instruments which are required in his profession, and such an account of the method of examining and rectifying their adjustments, as would enable him to obtain from them the most accurate results; but he found that, without greatly increasing the size of the book, he might materially add to its utility, by including in his plan the most approved Astronomical Instruments, that amateur astronomers as well as scientific travellers might have at hand a manual of instructions, which would enable them to use their instruments with the utmost advantage. Usefulness being the author's chief object, he has not scrupled to extract from the works of others whatever he found adapted to his own purpose; and to some kind literary and scientific friends he is under obligations, for which, if he had obtained their permission, he would be glad to thank them by name in this place. Of Surveying Instruments, those only have been described which are applied in modern practice, no reference |
