[Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 821 NEW YORK, September 26, 1891 Scientific American Supplement. Vol. XXXII, No. 821. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. Architectural.--The New Labor Exchange in Paris.--With views of the interior and exterior of the building II. Electrical.--The Construction and Maintenance of Underground Circuits.--By S.B. FOWLER.--A comprehensive article, discussing at length the various devices for protecting underground circuits, methods _of_ inserting the cables, etc. III. Engineering.--Railroads to the Clouds.--Sketches of a number of mountain railroads IV. Marine Engineering.--The French Armored Turret Ship the Marceau.--1 engraving.--A full description of the vessel, giving dimensions and cost A Review of Marine Engineering during the Past Decade.--A paper read before the Institution of Mechanical Engineers by Mr. Alfred Blechynben, of Barrow-in-Furness.--This paper, which is continued from Supplement No. 820, treats on steam pipes, feed water heating, twin screws, etc. V. Miscellaneous.--The Little House.--An article giving various hints about the arrangement and management of small dwellings, with special view to the best sanitary arrangements Stilt Walking.--A sketch, with engraving, of Sylvain Dornon, the stilt walker of Landes Remains of a Roman Villa in England Gum Arabic and its Modern Substitutes.--A continuation of a paper by Dr. S. Rideal and W.E. Youle.--With 26 tables A New Method of Extinguishing Fires.--Invented by George Dickson and David A. Jones, of Toronto, Canada.--Apparatus designed to utilize a mixture of water and liquefied carbonic acid VI. Medicine and Hygiene.--The Hygienic Treatment of Obesity.--By Dr. Paul Chebon.--Methods of eating, drinking, and exercising for the purpose of reducing fat.--An extended article, giving valuable information to people troubled with too much flesh VII. Photography.--Spectroscopic Determination of the Sensitiveness of Dry Plates.--A full description of the new plan of Mr. G.F. WILLIAMS, for determining the sensitiveness of dry plates by the use of a small direct vision pocket spectroscope