Improved Means for Testing the Light in Working Places Studios, Schools and so forth.
Year: 1898

page_text: Date of Application, 14th Nov., 1898
Complete Specification Left, 29th Nov., 1898-Accepted, 4th Mar., 1899
PROVISIONAL SPECIFICATION.
Improved Means for Testing the Light in Working Places Studios,
Schools and so forth.
1, HERMANN COHN, Professor Dr. Oculist, of Schweidnitzerstadtgraben 25, in
Breslau, Germany, do hereby declare the nature of this invention to be as
follows:-
This invention has for object certain improved means of or apparatus whereby
any one may be enabled to ascertain whether the light, at any place of work-
ing, studio, schoolroom, business saloon, or manufactory or elsewhere, is strong
enough for the purposes of the execution of close work.
In the drawings annexed hereto a construction according to this invention is
shown:-
Fig. 1, is an isometric general view of such an apparatus; and,
Fig. 2, is a cross section of the case or chamber wherein the test slides are
arranged and the observation is made.
In the holding case a, are arranged, in sufficient number, movable glass
sheets b, of grey or smoke color, the light penetration or absorption whereof is
tested and precisely fixed or previously ascertained photometrically.
The test sheets 6, are mounted in frames or carriers hinged conveniently to
the case a, by a cross spindle or rod 1. and such frames may be provided with
extension pieces 61, to provide for and facilitate the ready turning up, out of
the sphere or range of observation, so many of the sheets b, as it may be requisite
to make use of or to remove from use.
Combined with the case a and the sheets b, at a certain distance from the
glasses b, there is secured an object plate d, secured by arms such as c. Com-
bined with the plate d, are spring holding clips e, which will serve to hold ;to
the object plate a paper, card, or sheet inscribed or printed with writing or
printing characters of a certain predetermined size. Forward of the case a,
there is provided a screened observation piece and handle f, combined with the
case a, and the slides b, for carrying or holding purposes and for presenting the
apparatus conveniently before the eyes of the observer.
According to the work being done so do the requirement of light and clear-
ness vary. Thus for a work-place where large work is being carried on no
special strain is imposed upon the optic nerves and a lesser degree of light
intensity will be sufficient than would properly suffice for a room in which fine
drawing, painting, writing, reading, sewing, embroidering, and similar or kin-
dred fine work, which strains the eye, is being done and especially if same is
continued for any lengthened space of time. Again in a place where the sun
is shining, writing and reading can readily be carried on, or the light may be
too great but on gloomy days the light will not be sufficient.
In making use of this instrument, therefore, it will only be necessary to bring
the instrument up to the eye of the worker, and through the intervening sheets b,
to observe, under the prevailing condition of light intensity, whether the objec-
tive test sheet at d, is properly readable. If the light be insufficient the test
slides b, one or more must successively be removed until the characters on the
D
077

page_text: test sheet d, are clear to the observation; but on the other hand, if the light
be too intense, an additional sheet or sheets b, must be intervened between the
screen d, and the observer. According to the photometric degree of coloring or
obscuration of the sheets b, the same will be numbered to correspond to a regular
scale of the effective degree of light under which the work may be done.
The apparatus can be used for taking observations for day light as well as
for artificial light and where the light is insufficient it must be added to or
the work should be relinquished.
Again where the light is too intense or more intense than is requisite the
light should be obscured by screens or blinds.
This matter of readily gauging and adapting the light to the sight is a subject
of great importance at the present day having regard, alone to the increase of
studies in technical schools for both day and evening classes and so forth, and
the increasingly prevalent weakening of the sight of students and workers.
With this apparatus, not only is the degree of light tested but there is ascer-
tained the adaptability of each particular sight in reference to the degree of
light under which the work is to or ought to proceed.
Improved Means for Testing the Light in Working Places, Studios,
Schools and so forth.
I, HERMANN COHN, Professor Dr. Oculist, of 25,, Schweidnitzerstadtgraben, in
Breslau, Germany, 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:-
This invention has for object certain improved means of or apparatus whereby
any one may be enabled to ascertain whether the light, at any place of work-
ing, studio, schoolroom, business saloon, or manufactory or elsewhere, is strong
enough for the purpose of the execution of close work.
Referring to the drawings filed upon the provisional application, a construc-
tion according to this invention is shown:-
Fig. 1, is an isometric general view of such an apparatus; and,
Fig. 2, is a cross section of the case or chamber wherein the test slides are
arranged and the observation is made.
In the holding case a, are arranged in sufficient number, movable glass
sheets 6, of grey or smoke color the "light" penetration or absorption whereof is
tested and precisely fixed or previously ascertained photometrically.
The test sheets 6, are mounted in frames or carriers hinged conveniently to
the case a, by a cross spindle or rod b¹, and such frames may be provided with
extension pieces 62, to provide for and facilitate the ready turning up, out of
the sphere or range of observation so many of the sheets 6, as it may be requisite
to make use of or to remove from use.
Combined with the case a, and the sheets b, at a certain distance from the
glasses b, there is secured an object plated, secured by arms such as c. Com-
bined with the plate d, are spring holding clips e, which will serve to hold to
the object plate a paper, card or sheet inscribed or printed with writing or
printing characters of a certain predetermined size. Forward of the case a
there is provided a screened observation piece and handle f, combined with the

page_text: case a and the slides b, for carrying or holding purposes and for presenting the
apparatus conveniently before the eyes of the observer.
According to the work being done so do the requirements of light and clear-
ness vary. Thus for a work-place where large work is being carried on no
special strain is imposed upon the optic nerves and a lesser degree of light
intensity will be sufficient than would properly suffice for a room in which fine
drawing, painting writing reading, sewing embroidering and similar or kin-
dred fine work which strains the eye is being done and especially if same is
continued for any lengthened space of time. Again in a place where the sun
is shining, writing and reading can readily be carried on or the light may be
too great but on gloomy days the light will not be sufficient.
In making use of this instrument, therefore it will only be necessary to bring
the instrument up to the eye of the worker, and through the intervening sheets b,
to observe under the prevailing condition of light intensity, whether the objec-
tive test sheet at d, is properly readable. If the light be insufficient the test
slides b, one or more must successively be removed until the character on the
test sheet d, are clear to the observation; but on the other hand, if the light
be too intense an additional sheet or sheets b, must be intervened between the
screen d and the observer. According to the photometric degree of coloring or
observation of the sheets 6, the same will be numbered to correspond to a regular
scale of the effective degree of light under which the work may be done.
The apparatus can be used for taking observations for daylight as
well as
for artificial light, and; where the light is insufficient it must be added to or
the work should be relinquished.
Again where the light is too intense or more intense than is required the
light should be obscured by screens or blinds.
This matter of readily gauging and adapting the light to the sight is a subject
of great importance at the present day having regard alone to the increase of
studies in technical schools for both day and evening classes and so forth, and
the increasing prevalent weakening of the sight of students and workers.
With this apparatus not only is the degree of light tested but there is ascer-
tained the adaptability of cach particular sight" in reference to the degree of
light under which the work is to or ought to proceed.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. The improved combined apparatus for testing and gauging the light in a
work place characterised by a number of photometrically graduated or obscured
glasses b, arranged in the case a, with an observation opening in front and an
objective test carrying board c, d, e, substantially as and for the purpose herein
set forth.
2. In a light and sight testing apparatus as set forth the slides b, 62, hinged
at 61, to the case a, and combined with the test carrying object board c, d, e,
and front observation orifice, and holder constructed and operating as and for
the purpose specified.