The Red Cloud chief., 1878-03-28

They are supposed b. have been fsmi..
lar with the action ~ light on silver. by
which II IL blAckeped and pictures made.
The 6rst authentic record Of picture.
made by solar agency u found In Coop.
er's Rational R~erreations." published
In England In i77t An aesoun, IL Civ.
en- ~ the marking II bottie- ~ the sc-
ton on silver salts. Schielc mont esp.-
simcntct on the result ~ exposing tn
light paper made sensitive wiih salts VI
silver. lie recorded that the dccompo.
sition or b~larkrning wa most strongly
msrkei In the violet a y 81 light, and
next In orange and yellow. IL dis,ov-
cred that The most rcfrsngible part III
the air I. that which takes pictures.
Bolton and Watt. la their lnbor- Ia per.
feet the steam engine at Soho, probably
produced The first genuine sun. picturcs.
They were followed by Sir Humphrey
Davy and Wedgswood, WIN prepared
sensitive paper. and OH this placed fern
and other grasses. When exposed ~
light. the parts not covered were black
ened. The immagc ~ the fern APP
psared In white, but the inventors new
VT discovered a way Ia nv the picture.
When exposed Ia Ugh, I, soon turned
Ia black.
The experiments If Niepcc. from
1911 to 1927, led Ia the invention Of "A
crude ~heliotypc process, by the use 81
resin and bitumen. His pictures were
poor, but they induced Dagurrrc. In
1924, Ia Join In experimenting with him.
In 1889 Daguerre's process was given
to the world. When the news was first
brought to this country, II was regard
ed as Incredible. Only four years be-
fore. the public had been hoaxed by a
clc,erly-written account, in a New York
paper, II what Lord Ross had discoy.
cred In the noon through his big telc-
scope nj the Cape Of Good Hope. A
very graphic account of the moons in
habitants was given, and the article
gained In reality from u skilful use Of
scientific terms. II was several months
before the great moon hoaN' was cx-
plodcd. SO people were naturally skep-
teal about Dagucrre's astonishing sto-
ry. Onc ma In this city believed it
that was Dr. John w. Draper. rap.
plausc. lie had Investigated the sub
jcct. and his familiarity with physics
and optics gave him n clew to impor.
tant improvements, which hc soon an
nounccd.
Daguerrc's process was. in brief. To
place u piece Of copper plate with silver
over n vessel III iodine. when heated.
tho vapor Of iodine attacked the silver
and produced u coating Of iodidc Of sill
yer; the plate was then placed In acam-
era. and when the image fell on the son.
sitive plate, u picture WAS produced.
This was not apparent at first. Da-
guerre could see no trace Of u picture.
He slowed away the plates in a dark
closet; when he brought them out sew.
eral weeks afterward. behold, the mic
lures had come forth clear and distinct.
In searching for the agent that deyel.
opcd them. he discovered some mcrcu-
~. and. on vnporizing this, found at
last the needed substance. A gentle
man in Brooklyn has revived what NAV
be- called the ''lost art" Of Dayuerrc.
and now produces very perfect speci.
mems Of these pictures.
Landscapes was all that Dayucrre
could take; as II required IN hour To
fix the picture, no human endurance
WAS equal tn such n strain. l)r. Ora.
per found that by inverted lenses he
could shorten tho time. II was supposcd
that the yellow tingc Of the complexion
would he fatal to the picture. Draper
used to bring out a dredging box from
the Kitchen, and powder the face of the
sitter. who WAS then placed under blue
glass. II he could hold out for twenty
minutes. he secured n picture. In fact,
DIR. Draper often took his own picture.
-ttttSttv slnNN.a aats,.lx. Il, f. -
era for a half-hour. and then proceeding
tn develop the negative. hut the great
trouble with dag%uerrotypcs WAS the ex-
pense. E,ch picture required u new
plate.
An E~nglishman, Fox Talbot, pro
duced u silver paper photograph. which
WAS he germ Of the modern process.
Iaibot's process Is now carried on in
Germany. II was largely used during
the Franco-Prussian war for the making
uepf maps. An hour after n survey had
been made. an officer could be- provided
With u good map Of the hostile terrific.
y. Several chemists tried to find some.
nm better than paper to hold the sen.
llt'xed silver salts. The great develop.
nent came In 1891 when Schonbier, Of
basle' discovered gun-cotton. Cotton,
10 found. when exposed to nitric acid
became explosive, and soluble I'm a mix
nre OF alcohol and ether. The discoy-
Try Of this latter property was the
oundation of photography. When yun-
otton Is dissolved In alcohol and ether.
ullodion results; It forms a film on the
rirface Of = plate which holds the sill.
or salts. 1t gives us all our negatives
rom which thousands of pictures may
y struck OIL.
The process of taking a picture was
en- shown by the professor and his AS
stants. The camera obscure used was
large one, employed In \ recent for.
'ry suit 10 detect the spurious sigma
res to several checks. 1t was the re-.
rise OF those in common use, the pie
re being placed inside and the ground
ass plate without. A cap, the ~iectur.
said, Is nm important part of the
camera, but sometimes It plays sad hay.
90. Ono of the English parties who
went out to take views of the last tran.
sit OF Venus, returned home with many
plates. When these came to be deyef.
ooped;; Venus would not appear. II was
found that the cap over the Gamers had