New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1872-12-20

ITS RELATIONS TO MENTAL PROCESSEs-
GROWTH OF THE UNDULAToRY THEORY
LIGHT ANALOGOUS TO SOUND AND COLOR TO
PIICH-A SERIES OF LUCID EXPERIMENTS.
The hall of the Cooper Union was packed, TX
possible closely last night than at Prof TyndaPs
first lecture. Although seats were purchased for tho
course thoy did always contain the Same occupants
and was noteworthy that In majority OF cases "nero
gentleman absent from the scat no nao hheo on
Monday night his place occupied by lady insteaa
OF another OF his so that 1t resulted mat no
OF ladies largely increased. Tho interest OK
the audience was further Indicated by a remarks-
BILE punctuaity. It possiblc-and they VINO most
frequent lectures how rarely this is the case-o
hear all the opening words OF the speaker unlnter-
ruptcd newcomers trampng down the aisles Wills
pering 10 ushers and orowdng into seats Prof. Iyn-
dali commenced with q rapidly, and air Of having
much to do In time. that made 1t necessary for
a while 10 follow him closely; but, warming with MS
subject, especially when sounding the praises OF MS
countryman, DR.. Young he rose more nearly to strain
Of eloquence than his lectures here have hitherto
attained, aud the audience responded Win
a tribute OF hearty applause The optical
exhibitions we're more entertaining than on the
opening night, perhaps IA a reward for the patience
and close attention given to tho rather long prelude
OF history and disquston The interest does not IN
the least diminish as the minutes draw TO q con-
cusion. Has he stopped thought he was nc near
through How abrupt" Such ordinations heard
as the bowed adeu to people vino, ike Oliver
Twist, wanted More"
THE LECTURE.
We might vary anu extend experiments on light
indefinitely and they certainly would prove possess
a wonderful mastery over the phenomena. But tho
yesure of tho agent only would thus DO seeD not tho
agent ITSELF The human mind however Is SO constuteo
educated regards natural things That II can
never rest satisfied with this outward view OF them.
Brightness and freshness take possession Of the MIND
when it is crossed by the light OF principles which sho"
thu ~ IN he connected.
Let u.s. then, inquire what this thing Is that wo have
generating, rejecting, refracting, and anayzing
In doing this We learn that the life or the expert
mental philosopher Is two-fod. He lives. In his voca
tioD life senses. using his hands, eyes, and cara
his experiments but such question as that now De-
fore us carries him beyond the margin Of the He
cannot consider, much less answer the question, what
is light I" without transporting himself to world winch
underes sensible one and out OF which, in accord
ance with rigid law, all optical phenomena spring 10
realize this suosensble world II may use the TERM tho
mind possess o certain pictorial power l. has 70
visualize the invisible Ii be able TO form definite
Images Of the things which that subsensibe world con-
tans and to say that II such such state OF things
exist in that world then the phenomena which appeaf
10 ours must OF necessity, grow out OF this slate OF
things. IL the picture be correct. the phenomena ara
accounted for; physical theory has been enunclated
which unites and explainsithom ALL
This conception Of ysca theory implies. az you per
ceve exercise Of the imagination DO not be afraid
word which To render many Respectable
people, both In ranks Of science and out OF them un
comfortable That in the ranks .. science should
feel thus is think, proof that they have suffered
themselves be carried away BY the popular dennon
of great faculty instead OF observing ts operation In
their own minds. II to get anything done in
physical science, must invoke this faculty OF mag
nation. without Sc cannot take step beyond tho
bourne OF the animal world, perhaps not even to
the edge Of this B1t speaking OF imagination, do
not mean that roous power which those good and tmd
people appear to be alone acquainted with, but q we'll
ordered aud disciplined power whose sole function Is 10
form the conceptions which the intellect imperatiyey
demands Imagination thus exercised never rally sew
ers itself from the world OF fact This Is the sOrehouse
from which all it's pictures drawn; and the magic OF
it's art consists in creating things anew, Dnt IN 50
changing the magnitude, position, and other relations OF
sensible things render them ut for the require
ments of the intellect in the subsensible world.
PROCESSES OF SCIENTIFIC THOUGHT.
One OF my objects in these lectures is show you hy
what processes or in what way the scientific mind NJ
ains the deepest knowledge 1t capable OF attaining
which is knowledge OF the invisible sources OF phenom'
ena 1 will take. illustration or this SUBJECT the
case Newton. Before he began TO deal with ieh 10
was intimately acquainted with the laws OF elastic coli
Hson which all OF You have more OF less perfectly
illustrated q billiardtable AS regards the collision
of sensible masses Newton knew the angle OF Incidence
to be equal the angle Of reflection and he also knew
that experiment, shown In our last lecture had es-
taDllsne1
found in previous knowledge the material for theo
retic IMAGES He had only change the magnitude or
conceptions already in his mind TO arrive at the Ennis
sion Theory of Lght. He supposed light TO consist OK
elastic particles OF incoDcevabe minuteness shot out
with inconcevable lrapdity by luminous bodies Such
particles impinng upon smooth surfaces were reflected
in accordance with ordinary law OF elastic collision
Tho fact of optical reflection certainly occurred as II
light consisted of elastic particles ami this was New
toms sole justification for introducing them.
Bur this is not all In another important particular.
Also Newtons conceptions regarding the nature OF igt
were Influenced by his previous knowledge He had
been working the phenomenalo grsytaton, and mad
made his mind amid the operations Of this uni
yersa power Perhaps that mighty mind At this limo
was too freshly and deeply imbued with these
notions 10 enable II 20 unfettercd Judgment re-
gardng the nature Of light BE that as IL may Newton
saw the action OF attractive force exered
on the particles OF light. He carried his conception
out with the most severe consistency. Dropping YER
tcaIly downward toward the earth's surface, the
motion OF body accelerated as 10 approaches tho
earth. Dropping in the same manner downward on
horizontal surface say OF glass or water tue VeocV
Of the light particles when they come close 10 the sur
face was according to Newton, also accelerated. APP
preaching such surface obquey, he supposed the par
cles when it. TO be drawn down upon It, exactly
as proectle drawn by gravity TO the surface OF the
earth. This DETECTION by attractive force exerted
upon particles OF light, according "a NEWTON
refraction. Finally. IL was supposed that dinerepces
Of color might be due 10 differences ia the sizes OF the
particles; big particle, by its impact against the
netina producing color, ana small pariice or.
enanciated aud defended by Newton; AID you Will
observe that Il supply consists the OF
conceptions born in the world Of the senses to sub
sensible world.
THE PATH FROM FACT TO PRINCIPLE