Produced by Olaf Voss, Don Kretz, Juliet Sutherland, Charles Franks and the Distributed Proofreaders Team [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 392 NEW YORK, JULY 7, 1883 Scientific American Supplement. Vol. XVI, No. 392. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. ELECTRICITY AND MAGNETISM.--Improved Dynamo Machine. Eight figures. An Improved Manganese Battery.--By GEO. LEUCHS. The Cause of Evident Magnetism in Iron, Steel, and other Magnetic Metals.--By Prof. D. E. HUGHES. Neutrality.--Superposed Magnetism.--Elastic Nature of the Ether Surrounding the Magnetic Molecules. 3 figures. II. ENGINEERING.--The Westinghouse Brake. 2 figures. Hydraulic Elevators and Motors.--By B. F. JONES.--Bearing upon the Water Supply of Cities.--Cost of Water used.--Objectionable effects on Water Works.--Best method of arranging water supply.--Cause of Accidents.--Advantages of Water Motors over Steam Engines.--Rates for Water Motors. Water Supply of Small Towns.--Process of Softening Hard Water. Six figures. Improved Water Meter. Several figures. III. TECHNOLOGY.--Washing Machine for Wool. 1 figure. Increasing the Illuminating Power of Gases, etc.--By V. POPP.-- 3 figures. Preventing Iron from Rusting. An Elastic Mass for Confectioners' Use. Caoutchouc. Photographic Action Studied Spectroscopically. Salt and Lime. Renewing Paint without Burning. A Green or Golden Color for all Kinds of Brass.--By E. PULCHER. Vinegar. The Preservation of Meat by Carbonic Acid. On the Adulteration of Soap.--By Dr. H. BRACKEBUSCH. IV. CHEMISTRY.--Testing Olive Oil.--By Dr. O. BACH. On the Theory of the Formation of Compound Ethers. The Alizarine Industry. Reduction of Oxidized Iron by Carbonic Oxide. V. MEDICINE AND HYGIENE.--Bovine and Human Milk; the Difference in its Action and Composition.--By C. HUSSON. Cereal Foods in their Relation to Health and Disease.--By F. R. CAMPBELL. Moist Air in Living Rooms. The Developmental Significance of the Human Physiognomy.-- By E. D. COPE.--Numerous illustrations. VI. NATURAL HISTORY.--The Diamond Fields of South Africa. Sponges at the Bahamas. Testing Fish Ova for Impregnation. VII. MISCELLANEOUS.--The Production of Fire. 4 figures. St. Blaise.--The winner of the Derby. 1 illustration. * * * * * IMPROVED DYNAMO MACHINE.