Produced by Juliet Sutherland and the PG Online Distributed Proofreading Team at www.pgdp.net. [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 810 NEW YORK, JULY 11, 1891 Scientific American Supplement. Vol. XXXII, No. 810. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. BOTANY.--Cocos Pynaerti.--A new dwarf growing palm.--1 illustration. II. CHEMISTRY.--The Application of Electrolysis to Quantitative Analysis.--By CHARLES A. KOHN, B.Sc., Ph.D.--Applicability of these methods to poison determinations. III. CIVIL ENGINEERING.--The Kioto-Fu Canal in Japan.--A Japanese canal connecting the interior of the country with the sea.--3 illustrations. The Iron Gates of the Danube.--An important engineering work, opening a channel in the Danube.--1 illustration. The New German Ship Canal.--Connection of the Baltic with the North Sea.--Completion of this work.--1 illustration. Transit in London, Rapid and Otherwise.--By JAMES A. TILDEN. --A practical review of London underground railroads and their defects and peculiarities. IV. ELECTRICITY.--An Electrostatic Safety Device.--Apparatus for grounding a circuit of too high potential.--1 illustration. Experiments with High Tension Alternating Currents.--Sparking distance of arc formed by a potential difference of 20,000 volts. --1 illustration. Laying a Military Field Telegraph Line,--Recent field trials in laying telegraph line in England.--3 illustrations. Some Experiments on the Electric Discharge in Vacuum Tubes. --By Prof. J.J. THOMSON, M.A., F.R.S.--Interesting experiments described and illustrated.--4 illustrations. The Electrical Manufacture of Phosphorus.--Note upon a new English works for this industry. V. GEOGRAPHY.--The Mississippi River.--By JACQUES W. REDWAY. --An interesting paper on the great river and its work and history. VI. MECHANICAL ENGINEERING.--How to Find the Crack.-- Note on a point in foundry work. Riveted Joints in Boiler Shells.--By WILLIAM BARNET LE VAN.--Continuation of this practical and important paper. --10 illustrations. VII. MEDICINE AND HYGIENE.--Influence of Repose on the Retina. --Important researches on the physiology of the eye. The Relation of Bacteria to Practical Surgery.--By JOHN B. ROBERTS, A.M., M.D.--A full review from the surgeon's standpoint of this subject, with valuable directions for practitioners. VIII. MINERALOGY.--Precious and Ornamental Stones and Diamond Cutting.--By GEORGE FREDERICK KUNZ.--An abstract from a recent census bulletin, giving interesting data.