An Improved Apparatus for Testing the Sight.
Year: 1895

page_text: PROVISIONAL: SPECIFICATION.
An Improved Apparatus for Testing the Sight.
I, NATHAN LAZARUS of 89 Hatton Garden, London, E.C. Optician, do hereby
declare the nature of my said invention to be as follows:-
The object of my invention is to construct an improved apparatus for testing the
eye-sight whereby the inconveniences connected with the testing frames now in
common use, are obviated, the time occupied in testing being greatly reduced.
According to my invention I pivot or mount a disc, preferably of some light
substance such as wood, in a frame adjustably mounted on a base plate or stand.
This disc carries near its periphery a suitable number of lenses, concave and
convex, one of the apertures in the disc being without a lens.
On the spindle carrying the disc I mount a frame also capable of rotating on the
spindle, and provided with a suitable number of lenses (preferably five) so that by
the combination of the disc lenses with the frame lenses a decrease or increase in
the power of the lens may be readily obtained.
The apparatus is also provided with an adjustable frame or carrier for shutting
out the sight of the eye not being tested or for carrying additional lenses or the
usual tests for other optical defects.
'
At the back of the apparatus suitable means are provided for adjustably
supporting test types which may be illuminated from the back by a gas jet or other
illuminant.
:.
An improved. Apparatus for Testing
NATHAN LAZARUS 89 Hatton Garden London 'E.C. Optician, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly. described and ascertained in and by the following
statement:
My invention relates to a novel device for testing the sight by means, of a
circular disc, or frame supported on a suitable base and upright, containing lenses
of different power, capable of being revolved on its centre, and a second or
supplementary frame containing lenses, capable of being revolved, independently,
on the same centre as, and behind the circular disc, thereby giving a combination
of lenses. On the upright in front of the apparatus is a socket through which a
horizontal bar slides having a lens or disc holder at each end which can be moved
to the right or left at will. A telescope arm works in a socket on the upright at
the back of the apparatus, which is fitted with a card or disc holder-which disc
holder is also fitted in a socket so that the card or disc holder can be moved
towards, or away from the circular disc, by means of the telescope arin and also to

page_text: a
specifically and by the aid of the accompanying drawings-in which like letters
refer to like parts throughout the several views and in which
Figure 1 is a front elevation.
Figure 2 is plan.
Figure 3 is back elevation.
Figure 4 is side elevation.
"a" is a circular disc of wood or other material having lenses ","b" fitted in
a circle as drawn. <6
is a forked upright carrying the said disc "a
C
" which
revolves on spindle "d."
"e" is a base or stand of any suitable character with a vertical hole through the
; centre, through which lowest part of upright "c" slides and fitted with a set
screw "f" so as to allow the upright "c" being raised or lowered and held in any
desired position.
"
1
a
"
".g is a bar fitted with a lens or disc. holder """ at each end and sliding in
a socket "" so that it can be moved from side to side of, circular disc "
but prevented from coming right out of the socket "i" by the lens or disc
holders."" h:"**.
:
"" is a frame carrying a second or supplementary series of lenses mm revolving
on spindle "d" independently of disc " ,"fitted with knob or handle "/" for
convenience of moving.
a,
The centres of supplementary lenses are the same distance from centre of
spindle "d" as the lenses "6" in disc "a" are-thereby bringing one lens behind
the other and giving different combinations of lenses, as the disc "a
is revolved..
"
or frame "k"
"n" is a telescope arm working in socket "o" fitted with a set screw "p" and
having a disc or card holder ""at further end.
"
The disc or card holder "r is fitted with a pivot at bottom which works in a
sockets' on arm "n."
"
"
"
دو
It will thus be readily understood that disc or card holder " ? can be moved
towards or away from the disc " a by means of the telescope arm "n" and can be
moved to either side of the disc "a by means of the socket "o " and furthermore
that the disc or card holder """ can always be kept parallel with the disc "a" by
means of the socket "p." These movements and also the sliding movements
of "g" & "h" are for the purpose of using lenses at either side of disc "a" for
testing the right or left eye separately.
" t is a binding screw which is screwed into upright c and when turned exerts
a pressure on lens frame "k" so as to keep the same in any desired position.
u"u" are ornamental cover plates.
"
The disc or card frame."r can be fitted with a transparent or semi-transparent
disc or card and a candle lamp or any illuminant placed behind, either supported
from the apparatus or independantly.
:
Having now particularly described and ascertained' the nature of my said
invention and in what manner same is to be performed I declare that what I
claim is
(1.) A supplementary lens carrier and series of lenses revolving on the same
centre as a primary or first series of lenses. The lenses in both supplementary and
primary series moving in a path or orbit the same distance from the centre on which

page_text: they both revolve, bringing both series of lenses in line one with the other so that
when either supplementary or primary series of lenses is revolved a different
combination of lenses is given.
(2.) A bar or rod fitted with a disc or lens holder at each end sliding in
a horizontal socket across or from side to side of a lens frame in such a manner that
each lens holder will in turn project outside or beyond the lens frame when moved
to one side or the other and both lens holders being brought within the circum-
ference of the lens frame when bar or rod is placed in a central position with the
horizontal socket.
Dated 31st of October 1805
NATHAN LAZARUS.