Oe popular Science jSelos 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
Volume XXV. 
BOSTOK, JANUAKY, 1891. 
Number 1. 
CONTENTS. 
IMiLiAR Science. — Tlie Xeliula iu Lyra . 1 
pSome Novelties in I'hotograpliy .... 1 
Job and Railroads . . . . ' 2 
Studies in Plant Biology 2 
Geological Formation of the Earth — Its Evo- 
lution from CTiaos to Order — Relative Age 
of Fossils 3 
Lack of Social Harmony to the Age of the 
Aborigines of New ^Mexico 4 
Spring Rock Cave 4 
Antiquity of the Carpenter's Plane ... 5 
Where Pumice Stone Comes From .... 5 
Industrial Memoranda 5 
cScieutitic Brevities 5 
!E OuT-DooK WoKi,i>. — Correspondence 
Among ( hapters (i 
Chapter Addresses, New and Revised . . (! 
Geological Information Wauti'd .... (; 
Failure of Santa Claus <i 
I'lan for Studj- of Historical (ieology . . 7 
The Princeton Scientitic Pixhibition'of 188!) 8 
fElHTOKiAL. — The Fulminates !) 
A (iigautic Fruit U» 
Meteorology for November. I8!I0. willi Re- 
view of t lie Autumn 11 
Astronomical Phenomena for .lanuaiy. 1801 II 
The Phoenicians iu Britain 12 
C^uestions and Answers 12 
.Literary Notes 12 
[euuine and PiiAH.MACv.— Health and Dis- 
ease i:{ 
A Talk About Bacteria 18 
Monthly Summary of Medical Progress . . 14 
Headache and Acliiug of the F.yes ... 1.5 
\ Working Model of the Eye 1.5 
A Reflection upon Doctors. Mortalitv. and 
Athletics "... 16 
Sterilised Milk 16 
A Health Board on Chewing Gum .... 16 
Fatal Results of Lacing Among Savages . 16 
t'BLisiiEiis" Column . 16 
familiar §cienee. 
THE NT;BULA IX LYRA. 
We reproduce from La Natttre an engraving of 
a photograph of the «ell-known ring nebula in 
the constellati<m Lyra, taken by MM. Tkei'IKO and 
Haholkdin at the observatory of Algiers, which 
presents some very interesting features. 
The photograph required an exposure of six 
hours, which was obtained by two separate expos- 
ures, on different evenings, of three hours each. 
The original picture was only 1-50 of an inch in 
diameter, but was so clear and sharply defined 
that it could be enlarged sixty-four times, to the 
size of the engraving. 
This photograph shows, what was previously 
known, that the brightness of the nebulous ring 
is not uniform, but is concentrated at points 
roughly approximating to the shorter axis of the 
illipse : but the most remarkable feature is the cen- 
iral star or luminosity, which has never l)efore 
'"■en observed, all previous drawings and i>hoto- 
-:niphs only indicating a dark space, or one very 
laiutly lunnnous surrounded by the ellipse-shaped 
ling. This central star is entirely invisible to the 
'•ye, even when aided by the most powerful teles- 
copes, and only the sensitive gelatine film is able 
to receive and record for us the very feebly lumi- 
nous waves of radiant energy proceeding from the 
matter forming this wonderful celestial body. 
llianks to the power of the latelj- discovered dry 
photographic plates of gelatine and silver enuil- 
sion, we are just entering upon a new epoch of 
discoveries iu regard to the mysterious nebula', 
which have puzzled astronomers for so many years. 
The key has been placed in our hands, and it only 
remahis for us to use it and discover the true way 
m which the stellar systems were fonaed. ^V^' 
can hardly doubt that in such bodies as this we 
are witnessing the actual formation of a stellar 
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system like our own sun and its planets, ami 
enough has already lieen discovered to show that 
La Place's original nebular hypothesis, while 
maiidy correct, must he considerably modified to 
harmonize with the facts as at present known. 
Every day now brings new discoveries and illus- 
trations of the power of the means of astronomical 
research iu our possession, and it is impossible to 
set any limits to the knowledge of tlie celestial 
universe which we may hope to attain to by the 
aid of the spectroscope and the photographic pliite. 
SOME NOVELTIES IN PHOTOGRAPin'. 
The multiple portrait (Fig. 1) is an ingenious 
and amusing device of a Constantinople pho- 
tographer, M. Paboudijan, by which an indefinite 
number of portraits of the same i)erson may be 
taken simultaneously on a single plate. The prin- 
ciple involved is the familiar one of multiple re- 
flection from two mirrors placed so as to face each 
other. Fig. 2, a, show s the arrangement. AA and 
BB are the two mirrors, BB being the smallest; 
the sitter is placed at C, and the camera as sho\\ n 
in the illustration. The mirrors should bt; without 
frames, which would interfere with the success of 
the picture, and, as a part. of the light is lost at 
every reflection, a rather lengthened exposure 
nuist be given to bring out the mon; distant 
figures clearly. While, theoretically, the number 
of successive images is infinite, practically they 
very soon fade away into invisibility, owing to the 
loss of light at each successive reflection, as is 
very clearly shown in the engraving. 
The constantly increasing sensitiveness of the 
gelatine emulsions as now made, admit of excess- 
ively short exposures, and consequently allow ua 
to obtain very beautiful and remarkable instanta- 
neous views. Fig. 3 represents a man leaping 
over a settee, and caught by the camera in mid- 
air. The sharpness with which such a rapidly 
moving object was taken is remarkable, and indi- 
cates an extremely quick acting shutter. The hat 
just b^ing thrown fi-om the head is worthy of 
notice, as well as the peculiar expression of the 
face, which is involuntarily assumed by every one 
when making any sudden exertion of strength. 
FiK. 1. 
Fig. 4 is an instantaneous picture of a group of 
boys diving into the waters of the harbor of Mar- 
seilles, and is interesting both for the artistic atti- 
tudes of the group and for the superior mechanical 
execution of the'photograph. 
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A 
B 
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Fig. 2. 
The view of a fast trotting horse, in Fig. 5, is 
esijccially remarkable for showing the animal 
apparently suspended in the air, and proving that, 
at a certain point iu the trotting gait, all four feet 
of the horse are lifted from the ground at once. 
