[Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 NEW YORK, JUNE 6, 1885. Scientific American Supplement. Vol. XIX, No. 492. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 engravings. Qualitative Tests for Steel Rails.--By L. TETMAJER. A New Form of Small Bessemer Plant.--By A. TRAPPEN. Triple Compound Engines.--A paper read by A.E. SEATON before the Institution of Naval Architects. Early History of the Steam Jack. Bridge over the River Adige, at Verona.--13 figures. Pumping Machinery.--Mine pumps.--Direct acting steam pumps. By E.D. LEAVITT. Improved Gun Pressure Gauge.--2 figures. Measuring the Thickness of Boiler Plates. On an Express Engine. II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. Self-acting Shuttle Guard.--1 figure. Ruler and Triangle for Hatching. The Distillation of Sea Water.--1 figure. Aids to Correct Exposure on Photographic Plates.--An interesting paper by W. GOODMAN. Isochromatic Photography.--By FRED. E. IVES.--2 figures. Distortion from Expansion of the Paper in Photography. III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and Batteries.--A paper read before the American Association by C.E. FRITTS. Electricity Applied to the Manufacture of Varnish.--2 figures. Naglo Brothers' Telephone System.--3 figures. The Gerard Electric Lamp.--1 figure. A New Reflecting Galvanometer.--3 figures. IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment of the House of Parliament in Vienna.--2 engravings. The Casino at Monte Carlo.--An engraving. V. PHYSICS.--Determining the Density of the Earth.--1 figure. Physics without Apparatus.--The Porosity and Permeability of Bodies.--A Hot Air Balloon.--2 engravings. VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. Silk Worm Eggs.--With engraving. VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With engraving. VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section cutting machines.--Methods of preserving the tissues.--Preservative media.--Preparation for mounting tissues.--1 figure. Life History of a New Septic Organism. Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. * * * * * NEW SPANISH ARTILLERY.