[Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 446 NEW YORK, JULY 19, 1884 Scientific American Supplement. Vol. XVIII, No. 446. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS I. CHEMISTRY.--Tin in Canned Foods.--By Prof. ATTFIELU.--Small amount of tin found.--Whence come these small particles.--No cause for alarm. II. ENGINEERING AND MECHANICS.--The Windmill.--By JAMES W. HILL.--The Eclipse wind.--Other wind mills.--Their operation, use, etc. The Pneumatic Dynamite Gun.--With engraving of pneumatic dynamite gun torpedo vessel. Rope Pulley Friction Brake.--3 figures. Wire Rope Towage.--Treating of the system of towage by hauling in a submerged wire rope as used on the River Rhine, boats employed, etc.--With engraving of wire rope tug boat. Improved Hay Rope Machine.--With engraving. The Anglesea Bridge, Cork.--With engraving. Portable Railways.--By M DECAUVILLE.--Narrow gauge roads in Great Britain.--M. Decauvilie's system.--Railways used at the Panama Canal, in Tunis, etc. III. TECHNOLOGY.--Improved Pneumatic Filtering Presses, and the Processes in which they are employed.--2 engravings. Pneumatic Malting. A New Form of Gas Washer.--Manner in which it is used.--By A. BANDSEPT.--2 figures. IV. ELECTRICITY, HEAT, ETC.--Gerard's Alternating Current Machine.--2 engravings. Automatic Fast Speed Telegraphy.--By THEO. F. TAYLOR.--Speed determined by resistance and static capacity.--Experiments Taylor's system.--With diagram. Theory of the Action of the Carbon Microphone.--What is it? --2 figures. The Dembinski Telephone Transmitter.--3 figures. New Gas Lighters.--Electric lighters.--3 engravings. Distribution of Heat which is developed by Forging. V. ARCHITECTURE, ART. ETC.--Villa at Dorking.--An engraving. Arm Chair in the Louvre Collection. VI. GEOLOGY.--The Deposition of Ores.--By J.S. NEWBERRY.--Mineral Veins.--Bedded veins.--Theories of ore deposit.--Leaching of igneous rocks. VII. NATURAL HISTORY, ETC.--Habits of Burrowing Crayfishes in the U.S.--Form and size of the burrows and mounds.--Obtaining food.--Other species of crayfish.--3 figures. Our Servants, the Microbes.--What is a microbe?--Multiplication. --Formation of spores.--How they live.--Different groups of bacteria.--Their services. VIII. HORTICULTURE.--A New Stove Climber.--_(Ipomæa thomsoniana)_ Sprouting of Palm Seeds. History of Wheat. IX. MISCELLANEOUS.--Technical Education in America.--Branches of study most prominent in schools of different States.