of especial value in re-running lines of old surveys; also, new tables of the times and azimuths of Polaris when at elongation, for use in determining the true meridian with compass or transit, which with the rules given for interpolation are more accurate than any similar tables previously published. A full account is given of the system adopted in the survey of the public lands; and although the method is simple, it has, nevertheless, been productive of great results, by defining, with mathematical precision, the boundaries of lands in the new States, and thus settling their titles on an indisputable basis. In this connection official instructions and diagrams, issued by the U. S. General Land Office have been used, and, as the principal lines of a government survey must be run with reference to the true meridian, the Solar Compass and solar attachment to transit are described. A change made in the present edition, which must prove particularly acceptable, is the transformation of the article on Mining Surveying into a complete treatise, in which the location of claims on the surface, the latest and best methods of underground traversing, etc., the calculation of ore-reserves, and all that pertains to the work of the Mining Surveyor, are fully explained, and illustrated by practical examples. This improvement is due, substantially, to John G. Murphy, Esq., E.M., at one time Territorial Geologist of Wyoming Territory, an expert Mining Engineer of large and varied practice. In addition to acknowledgments elsewhere made, the undersigned is indebted to Professor Rodney G. Kimball, of the Brooklyn Polytechnic Institute, for valuable suggestions and labor, and to the Messrs. W. and L. E. Gurley, of Troy, N. Y., for their courtesy in furnishing him, for use, advance sheets of the last edition of their Instrument Manual and many cuts of their surveying instruments. COLUMBIA COLLEGE, N. Y., J. H. VAN AMRINGE, Editor of DAVIES' COURSE OF MATHEMATICS. |