Produced by Juliet Sutherland and the Online Distributed Proofreading Team at www.pgdp.net. [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 623 NEW YORK, DECEMBER 10, 1887 Scientific American Supplement. Vol. XXIV., No. 623. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. ARCHITECTURE.--Notes on the Construction of a Distillery Chimney--A new method of building lofty shafts, including a metallic frame and brick lining--3 illustrations. 9949 The Commercial Exchange, Paris--The new Paris exchange now in process of erection.--Present state of operations--1 illustration. 9954 II. ASTRONOMY.--The Yale College Measurement of the Pleiades.-- Dr. Elkin's work with the Repsold heliometer at Yale College. 9957 III. CHEMISTRY--New Method for the Quantitative Determination of Starch.--By A.N. ASBOTH--Determination of starch by its barium compound. 9956 Synthesis of the Alkaloids--A retrospect of the field of work so far traveled over by synthetical chemists, and future prospects. 9956 The Chemical Basis of Plant Forms--By HELEN C. DE S. ABBOTT --Continuation of this important contribution to plant chemistry, one of the most valuable of recent chemical monographs. 9955 IV. ELECTRICITY.--An Electrical Governor--A new apparatus for preserving a constant electromotive force with varying dynamo speed--1 illustration. 9952 Electric Launch--A French government launch with Krebs electric motor. 9954 The electric current as a means of increasing the tractive adhesion of railway motors and other rolling contacts.--By ELIAS E. RIES--A full review of this important subject, with accounts of its experimental examination. 9953 V. ENGINEERING--Benier's Hot Air Engine--A new caloric engine very fully illustrated and described--8 illustrations. 9943 Heating Marine Boilers with Liquid Fuel--A simple apparatus and recent experiments with the same.--3 illustrations. 9945 The Change of Gauge of Southern Railroads in 1886--By C.H. HUDSON.--The conclusion of the account of this great engineering feat, with tables of statistics and data--16 illustrations. 9946 Your Future Problems--By CHAS. E. EMERY--An address to the graduating class of the Stevens Institute, N.J.--A practical view of the engineering profession. 9943