The Norfolk Virginian. [volume] (Norfolk, Va.) 186?-189?, 1896-05-28
WONDERFUL TELrsCOpg.
It Enables the Observer TO Look over
Wall Higher Than Himself,


Great interest was manifested at the
recent meeting of the British Royal In
stitution In the new field glasses and
tereo-telescopes shown by the Zeiss
works at Jena. These Instruments pos
sess remarkable features different from
anything previously known. The OBJ
jects sought In their design are ID to
OBTAIN considerably larger field than
mat possessed by an opera glass Of sim
liar magnifying power, without the use
OF ordinary telesconic eyepieces. and
(2 TO enhance the stereoscoplc effect
OF the images seen through the tele-
scopes by placing the object glasses of
the binocular further apart than the
interocular distance OF the eyes. or that
OF the eyepieces. Two types OF glasses
are made-field glasses with magnify
ing powers from four to eight knlome-
| tiers, and stereo-binocular telescopes
with powers of eight to ten iiameters
In the stereo- binocular telescope the
object glasses can be moved through a
Wide range. They can be put so far
| apart sideways that II Is possible to
| stand behind good-sized tree with
| a glass at each side OF It. the observer
being thus hidden while he clearly sees
ell before him. Also II liz possible tn
| put the two object glasses close together
and look over wall which Is higher
| than the observer himself. The value OF
| this arrangement in military matters
| is too obvious to need mention. II Is
the realization of the Irishman's ideal
OF seeing round the corner A theatre
| glass made on this principle would be
| much appreciated when large hats are
| In fashion with ladies.
These instruments are so different
| from the usual kind of telescope that 1t
IS uiincuI to make their construction
| clear without diagrams, but London En-
eineer has end6avored to explain their
| principle as follows. AS Is well known
the simplest and most efficient type OF
| telescope is '%he astronomical, which has
| an achromatic object glass at one end To
| prlng the rays to focus, and an eye lens
at the other end through which TO view
\ the aerial image thus formed 1t has
however. me disadvantage of showing
OBJECTS inverted. which does not matter
| !or stars. NOW let us suppose such n
Telescope tube bent twice at right, angles
| Evidently 4 could not be seen through
| unless by the use OF mirrors or prisms
In the angles, but with their aid Il would
De possible to see over wall or round
corner; With two such tubes, 1t would
be possible Ito get a very pronounced
stereoscUpic effect. This Is a very rough
fashion, describes the Zeiss telescope.
immediately behind the object glass.
which is at flhe side-not the end-of the
tube. Is rtght-angled prism. from the
hypotheneuse of which the rays are to-
| tally reflected down The tube AT the
BOTTOM of 'uhe tube is another prism.
through the hypotheneuse OF which the
Icays pass to be totally reflected from
Its other two sides, and turned back par
allel 10 themselves. They are. however.
Immediately passed into third prism,
IN when they are al right angles and
delivered into the eye-tube
In the field glass the ARRANGEMENT IL
somewhat different. There are practI-
| cally two tubes side by side. with tn
| object glass at the end OF one and the
eye-glass at the end OF the other. The
rays go down the first tube, UP the sec.
ond. and again down the second, and
by this arrangement fairly long tele.
scope is compressed into the dimension
OF field-glass. Further in the passage
through the prsms the Image is erected
and thus the usual erecting lenses In the
| eyepiece are not necessary The raw.
undergo four successive reflections al the
surface OF the p,isms and emerge from
| sity."
The mechanical and optical details OF
the Instruments are exceedingly well
worked out. Each tube can be focused
separately, and such is the depth of TO.
Gus that the adjustment does not need
ever TO be altered except for very near
objects. The interocular distance Is
capable OF adjustment. and the owner
can mark the po.rt that suits himself by
spring catch, which, ;nowever, does
not prevent other persons setting the
tube TO suit themselves. The tubes can
| always be returned 10 the old position
without looking through them. These
glasses are not intended for use at the
theatre.