New-York tribune., 1902-02-09

dicated and they are described in popular rathet
than technical language. IL should oe unde,s,oel.
tails very fully. and has received much encourage
ment from expert engineers as 10 the eInelencS OF
Professor Todd would construct a hollow sphere
10 insure rfgiiitv M tube so feet Ions would be
inserted therein One-half projecting outside. and
opposite the aperture in The she'll Truss rods
enough would 6e used inside and out IT, TO pTSsent pse
dated that 5y moyins the latter with suitable 5
ject in the skies The Observers chair would be
hung gimbas, like compass. but otherwise
counterpoises in that vicinity would compensate
for the weight Of the outer half Of the ,TSe and and
movable would avert any shittins Of the centre T
furniture apparatus.
The sphere would rest in eOneavity in a bed
exterior Of the she'll II would float either in water
mercury, that none of the weight would be
carried directly by solid foundation ii Thus 1 abb
only a small amount Of power would be REQUIRED 70
therefor would be electric motors as in the best
control it all from his chair. Professor Todd is
confident that the sphere would be SO firmly
least wa6oling could occur The utmost precision
in following star seems to be assured
The favOrite way of mounting a refractinS teis-
the piIIsr One enables The instrument TO sweep
from east to west. and the otter from north 20
south The former is known the polar axis.
the Ions hours of o5servation by means of a driv-
ing clock. Professor Todd places his polar axis
outside the shell. in the masonry and aims IL AT
both the centre of the sphere and the north pole
of the heavens The particular method OF connect
ing 1t with the shell which he has adopted provides
for detachins the clasps. ~ 'chuckS teulpofaIllN
Obieet %a5s the instrument is being trained on give"
For convenience in Illustration no attempt is made
in the drawing to indicate the axis which permits
north and south movemt ut. This has all been
thought out, however. There would oe two attacn-
ments for that purpose. ore on each side OF the
she'll and so arransed as To be disconnectcds~nle
the instrument is being aimed.
down inside the sphere that could readily be done.
ond telescope could also be put parallel with the
first. Admission would be secured through a water
Todd has
near one or the cOunierPolSeS FfoIeSSoF lOgu uSs
devised a pendulum Indicator to hang inside the
latitude and longitude Oi the telescope $ avn
The first great advantage which this plan pos
StSes ~ tlat & - IN -
object glass The largest one now IN SetNlSe nas
an aperture of forty inches. The 50-inch objective
/ at Paris Is only suited to Photographic work The
lens for visual purposes was never 'lnlshed Fro-
fessOr Todd thinks that il might be feasible oy
/ his system mount object glass having an
aperture of anywhere from loII 20 s.Neh Lest-
The power Of instrument increases as the square
/ OF the diameter The ratio between a h-hch ana NJ
a 6C-nCh glass would be. Theoretically as 10 IS 20
20 Second. the size of the image depends on
the length Of the tube in proportion to the diam
( eter of the latter The ratio with most reIrac-
tube whose length would be from thirty
to fifty times its diameter. By prolonSlng the
focus too. a thinner and lighter lens is made pos
/ Aside from the optical merits Of this system. IL
proves a great convenience TO the working astron-
/ oIner and might Ue more economical than
/ The present stVIe of mounting In the latter the
/ Tessor ToId COMBINES dome with observatory. The
necSesi,v FOR cbaneine the level OF the observer
/ chair and moving the floor up and DOWN WITHIN a
range of twenty-five or thirty feet IS done away
An obvious objection 10 this novel type Of tele-
/ scope is that strong wind might disturb II ma