New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1880-12-26
SCIENCE FOR THE PEOPLE.
THE LUMINOUS CASCADE.

Tn an admirable series OF articles 10y LEWIS
Wright, on aOptics with the Lantern, nov
ment illustrative of the total reflection OF iight
is described: Get a twO-necked glass receiver
about three and half inches diameter. with
as large necks as possible, and ~ eacn neck
fix by cOrks glass tubes OF similar siAC, as
large as possible, not less than three-t -htns
inch clear bore, and one-half inch Is better
Black-varnish all outside, except circle three
inches diameter. opposite the nozzle meant 10
he horizontal, and adjust this close against anu
projecting into the lantern nozzle Vne hanko
nozzle with the objective removed) on wire
trinod filing with wafer first, and cOlklng the
tube i'm the horizontal nozzle till all Is arranged
Several feet higher, fix some sort OF supply
tank Ga bucket will do with IL bit OF tube hxed
10y cork IN the bottom ana coInecS VIII ILL.,; ,nt
ton nozzle by q flexible tube. FINAL ADJUST
the light at such distance from the condensefs
that the greatest possible amount is c0ncen-
trated into the space occupied Dy tne einiasion-
nozzle Having adjusted all this, ana lliled tue
tank. remove the cork from the nozzle and let
the water stream out in IA gentle curve into
bucket on the hOOI. The effect Is oeautiful,
even on this small scale. The jet Is IKE
stream OF living fire and II you nave coIoteu
glasses and slip them alternately INTO the
ordinary snde-stage OF the lantern, you s iII
blood red, blue, OF what color you desire. All
this is owing TO total reflection" III the wafer
did not Issue, and the cork was repiaceu oy
a ground glass stopper with hat poilsheu ehus,
the light from the lantern would De thrown
horizontally into the room. But 1t meets the
stream of water Oh every side at much more
than the angle of total IenectOn, ana 80 1t
cannot get ont but Is reelected from SIDE To slGe
all down the stream, making II Drillantly
luminous bv the small notes IN the water. tut
v0ur hand in the jet and it Is bathed IN Ight-
that light which cannot get ont OF the stream
except wheIe you thus break 1t UP.
MEASUREMENT OF RADIANT ENERGY.
Among the European scientists light and neat
have usually been regarded As essentially
different things. o. late years, however, some
observers have held that both were OEly
different manifestations OF radiant energy.
Nv the use OF o Rutherfurd grating and deli
cate thermal balance, Professor Langley, OF
the Allegheny PENN Observatory, recent y
succeeded in obtaining for the ilrst time lull
and exact measurements OF the distribution OF
energy in IA pure spectrum. where no lens OF
urisln had been used. and of fixing Its relative
amount as determined accurately by the
gths of light III all parts OF the visible
spectrum and in the ultra red. MI. Lang
ley's paper will he found IN tut IN Science
The essential result is of high theoretical IN
terest Ii Is, that heat and light as received
from the sun are now eXpermentally proved
so far rs such measurements can prove II, TO
be in essence the same thing. The OLD dellhea-
tiOns OF essentially different curves represeht-
ING heat and light must he b3nshed hereafter
from textbooks. The old views on tins sub
iect can no longer he maintained even by Euro
mean men OF science, who are prepOSSesSed IN
their favor This result, fulfilling what was
almost prophecy when made, quarter OF
century ago, by the cider Draper, ard Dellg
due largely to means which science owes 10 Mr..
Ruthcrfurd. may. If obtained, be most farly
claimed as largely due 10 the two Americans
whose names have just been cited.