motives; Manner of Setting Valves; Tables of Squares, Cubes,
Areas, etc., etc. By SEPTIMUS NORRIS, M.E. New edition.
Illustrated, 12mo. $1.50

$NORTH.--The Practical Assayer$:

Containing Easy Methods for the Assay of the Principal Metals and
Alloys. Principally designed for explorers and those interested in
Mines. By OLIVER NORTH. Illustrated. 12mo.

$NYSTROM.--A New Treatise on Elements of Mechanics$:

Establishing Strict Precision in the Meaning of Dynamical Terms:
accompanied with an Appendix on Duodenal Arithmetic and Metrology.
By JOHN W. NYSTROM, C.E. Illustrated. 8vo. $2.00

$NYSTROM.--On Technological Education and the Construction of Ships
and Screw Propellers$:

For Naval and Marine Engineers. By JOHN W. NYSTROM, late Acting
Chief Engineer, U.S.N. Second edition, revised, with additional
matter. Illustrated by seven engravings. 12mo. $1.50

$O'NEILL.--A Dictionary of Dyeing and Calico Printing$:

Containing a brief account of all the Substances and Processes in
use in the Art of Dyeing and Printing Textile Fabrics; with
Practical Receipts and Scientific Information. By CHARLES O'NEILL,
Analytical Chemist. To which is added an Essay on Coal Tar Colors
and their application to Dyeing and Calico Printing. By A.A.
FESQUET, Chemist and Engineer. With an appendix on Dyeing and
Calico Printing, as shown at the Universal Exposition, Paris, 1867.
8vo., 491 pages. $5.00

$ORTON.--Underground Treasures$:

How and Where to Find Them. A Key for the Ready Determination of
all the Useful Minerals within the United States. By JAMES ORTON,
A.M., Late Professor of Natural History in Vassar College, N.Y.;
Cor. Mem. of the Academy of Natural Sciences, Philadelphia, and of
the Lyceum of Natural History, New York; author of the "Andes and
the Amazon," etc. A New Edition, with Additions. Illustrated. $1.50

$OSBORN.--The Metallurgy of Iron and Steel$:

Theoretical and Practical in all its Branches; with special
reference to American Materials and Processes. By H.S. OSBORN, LL.
D., Professor of Mining and Metallurgy in Lafayette College,
Easton, Pennsylvania. Illustrated by numerous large folding plates
and wood-engravings. 8vo. $25.00

$OVERMAN.--The Manufacture of Steel$:

Containing the Practice and Principles of Working and Making Steel.
A Handbook for Blacksmiths and Workers in Steel and Iron, Wagon
Makers, Die Sinkers, Cutlers, and Manufacturers of Files and
Hardware, of Steel and Iron, and for Men of Scienc