The sun. [volume] (New York [N.Y.]) 1833-1916, 1878-05-26

10 DO different for different colors. Glass hap
pens to be a medium in which the dispersion OF
color thus obtained Is normal. that Is, in tho
order OF wave lengths from red to indigo).
There are. of course. substances the action Of
whose molecules upon tho ether is very differ
emit. and which cause abnormal dspcrsons. SO
called because the above order is changed.
1t II the primal lesson Of the prism. out Of
which the whole science Of spectrum analysis
has been evolved, that u beam OF white light is
not n simple thing. but may DO likened to IL rope
with an infinite number of strands Or If. by
some concerted action all tho keys Of a piano
are pressed down. the resultant sound made up
OF combination Of all the sounds upon the
Keyboard is perfect analogue TO that complex.
luminous phenomenon which we know as
white light. The reasoning which lies at the
bottom of all the now researches which have
made us as familiar with matter millions of
miles from us M we are with the matter Of our
globe. arises from tho complete establishment
Of this idea. that q ray OF white light Is uni
vcrsally composed Of many waves Of various
lcngths-just ~ the noise from the piano was
composed OF diverse musical notes. or sound
waves OF various lengths-whie each
light Of special color Is formed Of
single wave length or Of several wave lengths
in specific but less complex combination. SO
study Of light since the application Of photog-
raphy 10 the spectrum. that within the space OF
IA young mans lifo vast body of hard won
knowledge and ingenious speculation has crys-
tallized about the familiar phenomenon. that
solar ray, intercepted by prism and lens,
throws rainbow-colored image on u screen.
And the first decisive step in tho development OF
the new science was taken when it was demon
stratod that the difference between tho blue
light at one end Of that beautifully colored band
and the red at the other was almost identical
with the difference between high and low note
on the piano that what tho low notes are To
music the red waves revealed in the spectrum
are to light. and what the high notes are 20
music the blue waves are to light There was
something, therefore, curously pertinent in tho
blind mans comparison Of the color red to tho
sound Of Il trumpet
We are now ready to glance Mt the chapter in
which Mr.. Lockyer clearly and tersely formu-
latcs the basis OF spectrum ANALYSIS. Prcmis-
ing that all light scnders arc particles OF bodies
In vibration. and that without vibration there
will be no emission. he reminds us that the
reason why such things ms gas. candles flames.
the sun. and the fixed stars send us light il be-
cause they are In that state OF energetic vibra-
ton which We call heat. The difference be-
tween n source OF light. such as glowing solid
or liquid. which gives n continuous spectrum
upon analysis. and gas or vapor. which does
not. and which accordingly cannot afford us
White light. IL merely this-that in the case OF
gases and vapors produced by the atom -dlsso-
ciatng power OF electricity or Of heat their
molecules. which Offer colored phenomena.
differ only from those which in the case Of
solids and liquids gave US a continuous spec
trum In that owing to the action Of the
tnppmppe uu Oh .
much simpler constitution. Thus. IL we melt
metal. such ne sodium. we get at tho outset that
beautiful prismatic band called the continuous
spectrum but We come at last to n stage where
the spectra consist Of one. two. four. or, II may
be- hundreds oflines. But between these stages
are observed other intermediate spectra which
prove that the action of electricity or heat goes
on. the particles OF which matter is built up and
which yield white light when we get solids or
liquids TO radiate. grow more and more simple
in structure. until in the end we reach upon the
screen that dark line which attests the presence
OF sodium vapor. Now the function Of the spec
trum analyst is to apply these data to those ele-
mentary substances which lie within tho reach
of the hand. and those also about which we
know absolutely nothing except what the spec
troscope alone can DO made to tell us.
In regard to elementary substances. we have.
frst Of all, the fact that when we obtain q con-
tinuous spectrum we know we are dealing with
matter in n solid or liquid or. at all events
denscly gaseous state. but so far. we have not
n-certaned what particular matter it H. 1t may
be any OF the metals or any OF the compounds
which will bear a high tcmperaturc-bismuth
oxygen, nitrogen. or lime. But when W. have
got the matter simplned under the action Of
heat or electricity, So that its particles instead
OF being complex aud sclf-contained enough TO
al.
IN. ana produce colored light, then we discover
that no two substances with which we are ne
quninted exhibit ttho same sets Of limos
Hence. OF course the origin Of the
term spectrum analysis. since tho scru-
tiny OF the spectrum thus enables us
to difrcrcntia,e one substance from another
But experiment and comparison permit US TO
e. further and Say not only that such and su n
n substance bears unimpeachnblo witness t. the
existence OF such and such substance, but also
that such spectrum was produced by it, corre-
spending substance within n certain range Of
temperature. while still other conditions set
forth in Mr.. Lockyers treatise are not without
their influence. and are unerringly revealed.
To Illustrate by a concrete example. IL we take
vapor MS our lght-sender. we learn from the
spectrum its chemical composition its temper
ature troughy), and its density; and since the
precisely the same spectrum reversed. we can
detect its presence wherever it interVcnes be-
tween us and II luminous object.
1t is by following out considerations OF this
sort that the sun Of our own system and the
stars which are thu solar authors OF light and
life to other worlds than ours. have disclosed, or
are fast disclosing, their specific constitutions.
30 that We are able to declare the elements OF
which thoy are built up. the temperature at
which they exist. and in u large degree the ma
ture and extent OF their atmospheres and
tho way in which these Rtmospheres
vary from cycle TO cycle. We may
add that the reader will learn from this volume
exactly how much progress has been made in
that most delicate and difficult branch OF the
new science. cumulative analysis. He will also
" glad TO see the tables. which exhibit on tho
one hand those elements whose presence in our
sun is established beyond dispute. and. on the
other hand those for whose existence in that
luminnry there is merely a preponderancc Of
evidence.
Summary of Modern Canon Law.
useful work not only to Roman CathO-