Produced by Don Kretz, Juliet Sutherland, and Distributed Proofreaders [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 447 NEW YORK, JULY 26, 1884 Scientific American Supplement. Vol. XVIII, No. 447. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. CHEMISTRY.--The Bitter Substance of Hops.--By Dr. H. BUNGENER. --What gives hops their bitter taste?--Processes for obtaining hop-bitter acid.--Analysis of the same. II. ENGINEERING AND MECHANICS.--Improvements in the Harbor of Antwerp.--With engraving of caisson for deepening the river. Progress of Antwerp.--Recent works in the harbor. Bicycles and Tricycles.--By C.V. BOYS.---Advantages of the different machines.--Manner of finding the steepness of a hill and representing same on a map.--Experiments on ball bearings.-- The Otto bicycle. The Canal Iron Works, London. Marinoni's Rotary Printing Press.--With 2 engravings. Chenot's Economic Filter Press.--With engraving. Steel Chains without Welding.--Method and machines for making same.--Several figures. III. TECHNOLOGY.--Some Economic Processes connected with the Cloth Making Industry.--By Dr. WM. RAMSAY.--How to save and utilize soap used in wool scouring.--To recover the indigo from the refuse.--Extraction of potash from _suint_.--Use of bisulphide of carbon. IV. PHYSICS. ELECTRICITY, ETC.--Thury's Dynamo Electric Machine. --5 figures. Breguet's Telephone. Munro's Telephonic Experiments.--9 figures. Apparatus for Maneuvering Bichromate of Potassa Piles from a Distance.--2 figures. Magnetic Rotations.--By E.L. VOICE.--1 figure. Lighton's Immersion Illuminator.--1 figure. Foucault's Pendulum Experiments.--By RICHARD A. PROCTOR. --4 figures. V. ARCHITECTURE, ART, ETC.--St. Paul's Vicarage, Forest Hill, Kent.--2 engravings. Designs for Iron Gates.--An engraving. VI. ASTRONOMY.--A New Lunarian.--By Prof. C.W. MACCORD. --With 3 figures. VII. GEOLOGY.--Coal and its Uses.--By JAMES PYKE.--Formation of carboniferous rocks and the coal in the same.--Processes of nature.--Greatness of this country due to coal.--Manufacture of gas.--Products of the same. VIII. NATURAL HISTORY, BOTANY. ETC.--The Wine Fly.--The egg.--Larva.--Pupa and fly. The "Potetometer." an Instrument for Measuring the Transpiration of Water by Plants.--1 figure. Bolivian Cinchona Forests. Ferns.--Nephrolepis Davillioides Furcans and Nephrolepis Duffi. --2 engravings.