---- _Same._ No. 805. Mathematical theories of the earth. By Robert Simpson Woodward. From the Smithsonian report for 1890. Washington, 1891. 20pp. .10 ---- _Same._ No. 806. On the physical structure of the earth. By Henry Hennessy. From the Smithsonian report for 1890. Washington, 1891. 21pp. .10 ---- _Same._ No. 807. Glacial geology. By James Geikie, F.R.S. From the Smithsonian report for 1890. Washington, 1891. 10pp. .05 ---- _Same._ No. 808. The history of the Niagara river. By G. K. Gilbert. From the Smithsonian report for 1890. Washington, 1891. 29pp. .10 ---- _Same._ No. 809. The Mediterranean, physical and historical. By Sir R. L. Playfair. From the Smithsonian report for 1890. Washington, 1891. 20pp. .10 ---- _Same._ No. 810. Stanley and the map of Africa. By J. Scott Keltie. From the Smithsonian report for 1890. Washington, 1891. 17pp. .05 ---- _Same._ No. 811. Antarctic explorations. By G. S. Griffiths. From the Smithsonian report for 1890. Washington, 1891. 14pp. .10 ---- _Same._ No. 812. The history of geodetic operations in Russia. By B. Witskowski and J. H. Gore. From the Smithsonian report for 1890. Washington, 1891. 12pp. .05 ---- _Same._ No. 813. Quartz fibers. By C. V. Boys. From the Smithsonian report for 1890. Washington, 1891. 22pp. .10 ---- _Same._ No. 814. D. Koenig's researches on the physical basis of musical harmony, and timbre. By Sylvanus P. Thompson. From the Smithsonian report for 1890. Washington, 1891. 27pp. .10 ---- _Same._ No. 815. The chemical problems of to-day. By Victor Meyer. From the Smithsonian report for 1890. Washington, 1891. 17pp. .10 ---- <i>Same.</i. No. 816. The photographic image. By Raphael Meldola, F.R.S. From the Smithsonian report for 1890. Washington, 1891. 14pp. .10 ---- _Same._ No. 817. A tropical botanic garden. By M. Treub. Translated. From the Smithsonian report for 1890. Washington, 1891. 20pp. .10 ---- _Same._ No. 818. Temperature and life. By Henry de Varigny. Translated. From the Smithsonian report for 1890. Washington, 1891. 24pp. .10 ---- _Same._ No. 819. Morphology of the blood corpuscles. By Charles Sedgwick Minot. From the Smithsonian report for 1890. Washington, 1891. 6pp., 1 pl. .05