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

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

The Project Gutenberg EBook of Scientific American Supplement, No.
803,
May 23, 1891, by Various This eBook is for the use of anyone
anywhere at no cost and with almost no restrictions whatsoever. You
may copy it, give it away or re-use it under the terms of the Project
Gutenberg License included with this eBook or online at
www.gutenberg.net
Title: Scientific American Supplement, No. 803, May 23, 1891
Author: Various
Release Date: September 3, 2004 [EBook #13358]
Language: English
Character set encoding: ISO-8859-1
*** START OF THIS PROJECT GUTENBERG EBOOK
SCIENTIFIC AMERICAN ***

Produced by Don Kretz, Juliet Sutherland, Victoria Woosley and the
Online Distributed Proofreading Team.

[Illustration]

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.
* * * * *

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
* * * * *

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