The Dillon tribune., 1882-08-12
W;srella'.ts.
ru EYES o. sc1r1c1.

In . communicAtiou to the Herald: de-
cribinr the wonders Of the eyes which
s.ience has fashioned-telescopic, micro
,copic, spectroscopio, and, most marvellous
of Ill, Photographic eyes-Mr. Richard ID.
Ordinasy human eyesight, even when
strengthened and extended BY optical de.
vfees. possesses certain imperfections and
is used under certain difficulties. For In"
stance, at least tenth OF y. secs,nd ~ re.
uuired for the eye to take fufi look Ut
euy object. Even il the eye could nee an
object In lees time the image remain: at
least this time impressed on the retina.
Thus the eye cannot see an object which
moves very rapidly, and even when an eye
sees an object moving not too rapidly. or
moving in . circle % - continually TO
renew the impression (as when d burning
ro,; s vhirled round in dark room) the
ol .ct is not seen - II really ID, but the
., ,ssivs images. owing to the persistence
0. minous Impressions, are blurred to.
g. .r into IN image utterly unlike the real
oL,sct. Again, when an object 10 rapidly
changing IN shape the eye 10 often quite
unable TO go distinctly any one OF the
shapes which the object assumes. Thus
soarcely one Of the attitudes Of = galloping
horse can bs seen BY the human eye, inso
much that the dnsst pictures of . charge
or . raoo Ghow not one attitude which .
hosre really assumes when galloping. Yet
agai,i, the eye Il often prevented from
rscognising the true shape Of An object
which 10 itssH at rest, BY reason Of conttn.
mai nuctuations In the medium through
w IN the object 10 seen. a. for instance
when the telescopic image VI sun spot 10
examined through disturbed cir, or when
smaller details OF the solar surface are *.
amined through the air at ito very stiiisst
A LONG GAzK. 4.
On the other hand. but few weeks a~o
was looking in DR.. Henry Draper's Oh erva.
tory ct picture Of the great nebula in q, On
which had been two hours and twenty min.
utes forming itself on the retina Ut the pho
tographic eye oAscience other words, the
negative had required IN exposure Of this
duration. say nothing, though might well
cay much, ON the mechanical kin and inge.
nuity required to retain the telescopic i'm.
aye =, long unchanged In position. thoug'' all
the time the diurnal motion Of the heav.
ems va. carrying Orion round the heavens
n the rate lin reality slightly greater rate)
at which the sun moves in the sk.ex. nor
do | dwell on the optical and physical din.
culties involved in the task which Dr.. ORA.
per had thus successfully achieved. The
point wish chiefly to dwell upon il this.
that whore such . photograph 10 taken
science does in reality employ IN eye which
can give hours to single look. And let It
be noted that We 80 now but the beginning
Of the use Of the Photographic eye. which
can see In the ave-thousandth part Of .
second II need bs, or II need bs can rest it,
gaze for many hours on the same object,
seeing more and more AZ minute after min.
ute passes on. Yet already the swifter
view OF the Photographic eye has shown
details which the unaided human eye, or
that eye aided only by the telescope or mi.
cEo.cope, could never zoe. while the stead.
fast gaxs Of the Photographic eye has r..
vealed what It has been given to no human
eye to zee BY direct vision.
SEES AND DELlNEArEa
Note, further, that the Photographic eye
IN seeing, delineates also, whereas often
enough the eye kesnest to ace IL but it, .
skilled to guide the hand to delinsats at
b seen. and yet oftener the ordinary ~
can obtain but 20 brief view Of an obje i
that there b no time to draw what Il ecep
without trusting to memory, which in such
natler. Y too elten treacheroas. The 6nsss
ustsSure ~ s"A ss's-e s.'- :.:s@ - Gg8Wu .,
any human artist hes much lsss value than
have Janssen's instantaneous phot graphs
OF the sums surface. The best picture #
the great Orion nebula-which, despite Mr..
Delarue'a opinion in favor Of the view taken
with Lords Rosse's telescope, I consider to
BE- unqoestionably NJ. Trouvslot's picture