Scientific American Supplement, No. 803, May 23, 1891

ᱎScientific American Supplement, No. 803, May 23, 1891

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Title: Scientific American Supplement, No. 803, May 23, 1891
Author: Various
Release Date: September 3, 2004 [EBook #13358]
Language: English
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SCIENTIFIC AMERICAN SUPPLEMENT NO. 803

NEW YORK, May 23, 1891
Scientific American Supplement. Vol. XXXI., No. 803.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
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TABLE OF CONTENTS.
I. ASTRONOMY.--The Great Equatorial of the Paris Observatory.-- The new telescope recently put in use in Paris.--Description of the instrument and of its effects.--3 illustrations
II. CHEMISTRY.--An Apparatus for Heating Substances in Glass Tubes under Pressure.--By H. PEMBERTON, Jr.--A simple apparatus for effecting this purpose, avoiding risk of personal injury.-- 2 illustrations
Table of Atomic Weights.--A revised table of atomic weights, giving the results of the last determinations, and designed for every-day use
Testing Cement.--A laboratory process for testing Portland cement
III. CIVIL ENGINEERING.--The Compressed Air System of Paris. --An elaborate review of this great installation for the transmission of power.--The new compressed air station, with full details of performances of apparatus, etc.--10 illustrations
IV. ENTOMOLOGY.--Report on Insects.--Continuation of this report on noxious insects.--Their habits and how to cope with them. --18 illustrations
V. FLORICULTURE.--Lily of the Valley.--Practical notes on the cultivation of this popular flower.--How to raise it and force the growth
VI. MATHEMATICS.--The Conic Sections.--By Prof. C.W. MACCORD.--Examination of the four conic sections with a general definition applicable to all.--6 illustrations
VII. MECHANICAL ENGINEERING.--The Builders of the Steam Engine--The Founders of Modern Industries and Nations.--By Dr. R.H. THURSTON.--Prof. Thurston's address before the Centennial Celebration of the American Patent System at Washington, D.C.--The early history of the steam engine and its present position in the world
VIII. MISCELLANEOUS.--The Breeds of Dogs.--Popular description of the different breeds of dogs most affected by amateurs.--6 illustrations
IX. NAVAL ENGINEERING.--Modern Armor.--By F.R. BRAINARD.--The development of modern ship armor, from laminated sandwiched and compound types to the present solid armor.--9 illustrations
X. PISCICULTURE.--Restocking the Seine with Fish.--The introduction of 40,000 fry of California trout and salmon, designed to restock the Seine, depopulated of fish by explosions of dynamite used in breaking up the ice.--1 illustration
XI. RAILWAY ENGINEERING.--Improved Hand Car.--A novelty in the construction of hand cars, avoiding the production of a dead center.--1 illustration
XII. TECHNOLOGY.--The Tanning Materials of Europe.--The natural tanning materials and pathological or abnormal growth tanning materials described and classified, with relative power
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THE GREAT EQUATORIAL OF THE PARIS OBSERVATORY.
The great instrument which has just completed the installation of our national observatory is constructed upon the same principle as the elbowed equatorial, 11 in. in diameter, established in 1882, according to the ingenious arrangement devised as long ago as 1872, by Mr. Loewy, assistant director of the Paris Observatory.
We shall here recall the fact that the elbowed equatorial consists of two parts joined at right angles. One of these is directed according to the axis of the world, and is capable of revolving around its own axis, and the other, which is at right angles to it, is capable of describing around the first a plane representing the celestial equator. At the apex of the right angle there is a plane mirror of silvered glass inclined at an angle of 45 deg. with respect to the optical axis, and which sends toward the ocular the image coming from the objective and already reflected by another and similar plane mirror. The objective and this second mirror (which is inclined at an angle of 45 deg.) are placed at the extremity of the external part of the tube, and form part of a cube, movable around the axis of the instrument at right angles with the axis of the world. The diagram in Fig. 3 will allow the course of a luminous ray coming from space to be easily understood. The image of the star, A, toward which the instrument is directed, traverses the objective, B C, is reflected first from the mirror, B D, and next from the central mirror, E F, and finally reaches O, at the ocular where the observer is stationed.
This new equatorial differs from the first model by its much larger dimensions and its extremely remarkable mechanical improvements. The optical part, which is admirably elaborated, consists of a large astronomical objective 24 in. in diameter, and of a photographic objective of the same aperture, capable of being substituted, one for the other, according to the nature of the