The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1866-02-17
CITY INTELLIG ENUE
EFor AdaitionaI oitg I,teltgence see FlflA Paas.l

The Professor illustrated his lecture by number Of
beautiful experiments, which aveinnite satisfaction
to the large audience assembled. The experiments
consisted of spectrum analysis and very pleasing
series Of dissolving Views About eight O'clock the
Professor made his appearance on the stage. He
received with applause and spoke substantially as
foows:-
Ladies and gentlemen;--on previous occasion 1
had the honor Of explaining to you how luminous
bodies communicated that vibratory movement which
constituted their light to the surrounding fluid in
series Of waves. by which it propagated In all
directions and conveyed to distant objects and places.
This evening propose with yon to follow some OF
these they fly and to Investigate the nature
those changes they sner when encountering dense
but transparent substances such as glass, water and
the like
In studying these actions we must condne our at
tenton first to single series OF successive waves,
such might I'm some sort be indicated by what is
commonly called n wave line, and which we denomi-
nate a ray of light This, have before seen by
experiments proceeds in perfectly straight
line, unless interrupted in its progress as for example
in the following case;-Suppose that ray of light
comes obquely upon dense body. such as plate o.
glass it enters this surface 1t experiences bend or
breaking ofs straight path and pursues its course
within the glass In n direction nearly perpen
dcuar to the surface by which it entered than It's
road before on leaving the glass upon the other side
this action exactly reversed and II the two surfaces
OF the glass parallel the ray thus restored to its
original direction. "f .I..
This action is called rerdction and by your permls-
sion will endeavor by the of simple illustra-
tion, to give general indication to its cause
First, however, must premise that by careful ana
direct experiment It has been determined that ight
waves rays retarded in their advance through
dense bodies.
Let u.s. then, imagine that body of troops was ad
vancing obliquely this stage towards the or
chestra, and continued their march into the house.
The footghts, the front of the stage, and also the
seats beyond present obstacles which would retard
the rate of advance as we may easily imagine but
what effect would this have upon its direction Clearly
this .t..oI
Suppose the right file of the column first to reach
the stage 'front.' he would be retarded while his LETT
file would still be advancing freely ana In IKE man.
ner with the rest of the line which would thus be
swung round, to advance in a direction more
nearly perpendicular to the face of the obstruction
than their previous The reverse OF this would
clearly happen in leaving such obstructed region
for clear ground and opposite and equal detection
would the result Thus Is IL with the wave or ray
of light It's front is thus swung round and its course
changed by the process termed in oneword rerdcon.
To illustrate this action, we have many curious ex-
periments Thus cause broad arrow arrow ag Of light to to
taken of this and set Off TO one side by the nterpo
MAKES a double elbow in the light which passes
through it, and thus sets this part away from the res
Again tank Of fresh water. containing fish lizards
G1nF and Is "S Is o @
perceive upon the screen Into tins SAT- water Is now
faces of contact the light rays are bent as by the
away from some points and concentrated upon others
develope light and dark markings in the I curling
some submarine volcano casting out its clouds of
In fresh tank of water fountain of crimson fluid
was caused to flow, in like manner producing on the
st Jet Of aTy des1 in nen a We
Various changes in color illustrating other points in
relation this subject, shown with this appa
ratus with the most beautiful and Impressive effect.
sunset, Hat With its changing crimson clouds unfolding
upon the then came the grand gathering ofhe
storm Clouds rolling and tumbling together in vast
confusion but presently melting away into clear ex-
After these clear glass goblet its place upon
the screen in towerng magnitude Into TINS & stream am
as the filled it the goblet became black light
6ens az The stem e Of this glass broken
by the means as the arrow before yet 1t stood
After these general illustrations of reraction Pro-
e0n prsm how this bent ray Of light and
how bending different colors differently in proper.
dispersed divided ray flighinto the colors ofthe
A splendid spectrum more than ten feet in length
was then thrown by the Professor from lantern at
the front ofthe stage upon movable screen, IT. how
ever, the light used were not white but OF single
but single band OF the color in question Would be
shown upon the screen, The line was here removed % ed
glass which in the % flame y Yields SsS pure pure
to take TIE place OF the spectrum upon the screen
bodies RoS P v nge Sa Wa 1GSs
flames ofmingled gas and air with FIVE rings OF lamp
when the flames were colored yellow crimson blue
violet, and green respectiyey ,roa % o.oa,oo .,,s
effect is extremely small especially If the light is con.
@ BY ns action % the OF & Prm nFC eP II nes
bands. This property thus becomes the means Of a
which, by examining the flame in which an unknown
body is heated through a prism with proper appli.
certain bright colored lines which then make their ap;
10 @ sod S6P Gng 20 Svs
tinuous spectrum; it was the vapor of soda driven
off from the glass which produced the yellow.
nebuis, such as the dumb-beil the great ne6ule in
Orion, &c not before supposed, vast clusters Of
but simply gaseous systems, since they show q
few lines only when examined by this prism test,
Again, the white light from solid body passing
through a highly heated luminous Vapor, loses such
coored rays belong to that vapor Itself these wave
motions are are given % sG ba 5y
deprived these special parts ana u anayzeu oS @ te
bese coors S should have been This is the case with
the light from the sun and from the fixed stars 4
RufEeTrd Of New YORK showing vast number
these lines was here projected upon the screen MANY
produced by certain substances, hence We judge that
these bodies exist In the atmosphere OF the sun Ihe
pOnding dark Ones and conclude such are not pre-
sent in our lumnary. We have thus, by the potent
buie, hut actually dndtized The sun.
Passing from the prism, whose other uses we will
this occasion to discuss Illustrate
the next simple instrument in which the process o.
refraction is made useful is the lens This In It's or
opposite convex curved surfaces. Let us see how
these will act by their refracting power upon ray o
BY means of luminous coored diagram projected
upon the screen the action of lens and the manner
IN which it produced an image Of any object, wa
then very simply and clearly explained ana by mean
of other diagrams the known as spherical ant
chrcmatic alteration were shown and their means o
correction made manifest.
remarked:-We hav from time TO time appealed 4
the sister science of sound in confirmation or Illus
notice that the parallels which has served usso ofte
does not desert us here. We may have lens TO
Monsieur sondass devised this curious experiment
RrepaTed sTS % sa ed SL CAPS t on bras ring