Produced by Juliet Sutherland and the Online Distributed Proofreading Team at www.pgdp.net [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 312 NEW YORK, DECEMBER 24, 1881. Scientific American Supplement. Vol. XII., No. 312. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. ENGINEERING AND MECHANICS.--Improved Fifteen Ton Traveling Crane. Designed for service in the construction of Port Alfred Harbor. South Africa. 3 figures. 4967 Improved Steam Boiler. 1 figure. 4968 The Elevated Railways of New York. 4968 Some of the Developments of Mechanical Engineering during the Last Half Century. British Association Paper. By SIR FREDERICK BRAMWELL. The steam engine.--Evaporative condenser.--Steam navigation.--Marine governors.--Light engines and boilers.--The Perkins system.--Ether engine.--Quicksilver engine.--Locomotive engines.--Brakes.--Motors.--Transmission of power.--Compressed air locomotives.--Hydraulic transmission of power.--Electric transmission of power.--The manufacture of iron and steel.-- Bridges.--Machine tools.--The sewing machine.--Agricultural machinery.--Printing machinery. 4968 Amateur Mechanics: Metal turning, 29 figures. Rotary cutters, 12 figures. Wood-working and lathe attachments, 9 figures. 4971 A New Method of Keeping Mechanical Drawings. 4978 Achard's Electric Brake for Railway Use. 2 figures. Plan and elevation. 4974 II. ELECTRICITY, ETC.--Electricity. What it is and what may be expected of it. By JACOB REESE. 4974 Electric Light Apparatus for Photographic Purposes. By A.J. JARMAN. 2 figures. 4976 Desruelles's Electric Lighter. 1 figure. 4976 Solenoid Underground Wires in Philadelphia. 4976 Dr. Herz's Telephonic Systems. 2 figures. 4976 Decision of the Congress of Electricians on the Units of Electric Measures. 4977 Secondary Batteries. By J. ROUSSE. 4977 III. TECHNOLOGY AND CHEMISTRY.--Domestic Sugar Production. 4980 M. Garnier's New Methods of Photo-Engraving. By Major J. WATERHOUSE.--Photogravure.--Photograph printing by vapor.--Atmography. 4982 Dangers of Pyrogallic Acid. By DR. T.L. PHIPSON. 4982