The sun., 1894-11-11

How mlsh power VIII ~ teq"H0' w :"
:" The power will be very smsll. A one horse. =.
sfSs eS9spH Ssstms S he ss S,ss
be empls TO drive the requisite electr9 g ~
Ths force will SS ons lie
through the wSier. The water currents vii y, not :
lew moments. ON With a pslf Of trunplons st;
tached to the tube at the water line and
an 'e eunSiorially G ON mouhted ld telescope With.
out amy weight whaeysr on the beeringi Of IN the
be lightened by an amount nearly eqnsl TO the
weight of the polar axis, and there Will then be
sss there eS viii Hfisnt Se tS SROdS sad
| will mot be convenient 70 use the instrlmesnt si.
%Jf si1 sosf ssFstis e o pos E' 'SSd PTe
Ter 70 have the instrument az perfectly n,ne, W,
ss9Ses q al Ss .ssS rf + That no w doSs Ss 2s Sa
more Of work that would only be OF use on rare
What kind Of a reflector will II bel"
| THE KIND OF REFLECTOR.
| II have designed II on the Newtoniqn plan.
| In all refectors the light passes down the tuDe
bring It to a focus in the tube at a distance de-
pending upon the shape Of the mirror Before Before
| on a small mirror and again reflected to an eye
piece located IN conyehient position, on, for % o9i
Is n hI and sS Gr sSs i
Il down the tube through q hole in the centre OF
the large mirror The eyspese !: placed 9b in !, this
manner precisely similar to that necessary with
~ srr, ordinary ,S reflector: H In tine EasseErslaa
inside the focus, and the light is also shown
through the centre Of the large mirror. and the
Is obvious that neither Of these forms would do
iSr the floating telescope. The other form Is
light from the large mirror il received on a
small fiat mirror placed in the upper end of the
grees. The image OF the object looked at is thus
formed at tho side Of the tube, through hole
lower end Of the tube completely closed, and is
specially suitable for the method OF hotation
but is not the fiat mirror in the tube draw
interfere with the The ID defniion n any way. il
would have diameter Of one foot at the out
pE9SWtS6s @RoEtapsSs, bs 'Ss ~ the srv.
TEN-FooT MIRROR.
About ten feet in diameter. IT, as I expect, |
can procure the material for one Of that size, |
twill be of silver on glass; This IL Aim Of |
the face, not on the back Of the glass. II Is ex-
it The 6 an asa @ mrrar c
this purpose. II is deposited on glass Of
1es s there .hoHa SSr be- on srss sss
difhculty N making one Of speculum metal l
may say that s the mounting Of this rensseipg
the making OF instruments Of this kind. and but
Tor recent improvements should have hesitated
TO recommend its construction for Photographic
purposes. Within the last month. however DR..
Johnstone Stoney has devised a most ingenious
arrangement for supporting tesscopic mirrors
upon an air support grad duating the pressure ac-
cording TO the angle of inclination of the tele-
tus In It's present form is a valuable step In ad-
vance, and is doubtless susceptible of improve
Of the most troublesome problems in the en-
deavor to obtain really good rejecting tele-
scope, and shall utilize II or n modification of
Il IN the ten-fOOt instrument"
What poa, viii win be the cost Of such a mirror'"
- How large Is the spherical part Of the tube 2"
PROVISIONS FOR THE OBSERVER.
Twice the tubes diameter, or twenty feet.
its position In the tube will be such, as you see
above water will be six feet in length. and the
holes for the eSepeces as in the model, will be
Be 81 e{s S sRG Rs
ment men, 9f the observer, is never more
sSS that SHOWN IN s Il. sa4s
e eSe Sea end e
ali times 10 overcome the rotation of the tube
as the instrument moves In right ascension, |
degrees round its cireu2fets6cs. i' and moans nn
III ba tat i mirror and cell IN collar SO as TO en-
of Thirty degrees By these means th the y msT. of
he celestial object to be observed could be sent
sa the or Sf aS
Inc arscsi2n ,II1 most eonyenient to himself"
The observer will simply set pair of point
,rs at the eye end to the particular readings hs
Hishes Wish, ,,i snd then press button. The instru
he telescope on its axis Til that position Is at
Hay S1$ iSPs viii I 4 ! s%Es ,.p p complete ~"
rom the date Of commencing"
What n, is your e estimation of its total cost :"
what great advantages do you look for from | ,
he use Of the ten-foOt rehector2" :
WHAT Is HOPED FOR FROM THE NEW TELESCOPE d
= h,Gsnerally speaking, all those advantages 9
which a come from increased optical power. Dur
sneed nftsen INCHES IN the size Of our refrac-
is shss ne. 1t he or fsTsss % being now forty inches
rstraeior of sixty inches All those Who S''s 1se
arger the aperture the fewer are the oppor
nnities on which IL can be used with advan- e
5 to, whether tlre useful limit OF amer. G
nre IRE has not already been reached. except q
ayored locslites as AreaSpa' for instancs n suSn
he conditions Of life at these Isolated stations o
in the esss 6f and though
lth the difficulties temporarily, they will not d
lterfcre with The steadiDess OF the WORK that A
elays ,I OF WORKERS have already been found Y
W 'Sme snnesr sases which pen is open 70
s,s1s n,srabhis system is independent to great u
aentiy Se %, csn atmospheric disturbance. Conse-
,stEuinents lts conveniently within the confines 81
ciIillzatlon, great gain in itself. pl
M More9Ntr' Ne shall he able 10 uss with advan- r.
tents M or far greater power than have hitherto
rem rem ouilt anu instrlments whose value was | of
sry doubtful 80 long as the old system Of eve o'
DserHstlons was the only one available Pho bc
'sIaphy, IN other words has created a demand al
" larger and larger Telescopes Whenever we IL
ouble the diameter Of the aperture we get four so
@ nles ihe light In photography this is Of MAY
NUN Importance, because by doubiin9 he OF
amelrr we can obtain result, say in one ag
lnr' Nhlch previously required four. A twelve. bI
m ,ui U UVNppsuIe, other things being equal should pl
We We US as good a photograph as forty-eight In
,uFs eAHishre With an instrument OF half ihs pl
~, Now, we can certainly obtain these iarge bu
stiunehla ~ The form ot renecLors while lila iii
TRACTORS. " 'A' i"'hl ot hv
VARIATION IN THE POWER or TKrscoDvs Al
. .Ihn IalInar ~ - - - A