Year: 1895

page_text: Date of Application, 3rd Dec., 1895--Accepted, 22nd Feb., 1896
Fig. 5, a detail-sectional view.
Similar reference letters in the several figures indicate similar parts.
The body or case of the instrument consists of a tubular casing A. mounted upon
a bracket B pivoted upon a rod or standard C supported in any suitable supporting
frame, as a ring C, to which are attached legs C 2, forming a tripod, a securing
screw c serving to hold the standard in position. The rear end of the tube A is
open and at the forward end is arranged a sleeve or eye-piece D carrying in its
inner end a diaphragm D¹ in which is mounted a small negative lens E, while upon
the front D2 of said eye-piece is arranged a small diaphragm D4. The eye-
piece D is not rigidly attached to the tube A, but the end of the latter is provided
with an annular groove a into which project two or more small screws d and it is
provided with a scale d' on its outer periphery, marked off in degrees, with
which co-operates an index a 2 on the upper side of the tube A, so that the eye-
piece can be rotated on the tube and the amount indicated by the scale, as will be
described.
Pivoted upon the pin or screw f on the eye-piece are two discs or lens-
carriers F F, each having a series of apertures in which are arranged cylindrical
lenses f¹, f2f3 etc., the axis of said lenses being radial to the centre on which
the discs F F are adapted to be moved. These discs have their edges milled and
inclined toward each other and are provided with marks on their peripheries
corresponding to the lenses f1f2 f3, etc., and indicating the strength of the lens
exposed through the aperture in the eye-piece, and suitable apertures 9 are
arranged in their faces with which co-operate suitable spring-pressed pins /* adapted
to maintain the lenses in the discs in line with the aperture in the diaphragm D 4.
One aperture in each of the discs F F is unprovided with a lens, and the markings
on the peripheries of the discs are so arranged that when the zero mark is in line
with the index a 2 (as in Fig. 2) the blank apertures will be in line with the eye-
piece, and the lenses in the forward disc range in strength say from 25 to 1.25,
and those in the second disc from 1.50 to 7.50, and obviously two lenses, one in
each disc, can be so combined as to provide a higher power when desired. Any
ΓΟ
027

page_text: other suitable means can be provided for holding the discs in proper rotative
position than the spring-operated pins shown.
G indicates a split-ring arranged in the annular groove g¹ formed on the tube A,
carrying an eye-shade G₁, in the form of a blackened disc so that the patient may
keep both eyes open when using the instrument.
•
Sliding within the tube A is an inner tube or sleeve H, constituting a lens-
carrier, having at its forward end an achromatic objective J, and the lower side of
said tube is provided with a rack j with which meshes a pinion on an arbor K
journalled in the bracket B, the ends of said arbor having hand-wheels K' and
on one side a disc L having a scale marked thereon (indicated by the word
convex on the drawing) and with the scale co-operates an index L₁ on the side
of the tube A.
"
A slot is formed in the upper side of the tube A, through which the lens-
carrying tube is visible, and upon the latter is marked a scale indicating
degrees of nearsightedness or myopia (indicated by the word ". concave " in the
drawing).
M indicates a slotted plate fastened in position by a screw M¹ and having two
indexes on opposite sides, one m co-operating with the scale on tube H, and the
other m' with a scale marked on the tube A and indicating the distance for which
the instrument is focused. The relation between the eye-piece lens and the
objective is the same as that between the eye-piece and objective of an ordinary
telescope or opera-glass, that is, so that the observer can see clearly the distant
objects, as an astigmatic chart, when properly focused.
The method of using the instrument is as follows;-First set the double index M
so that the index m³ shall agree exactly with the range in which the instrument is
to be used, as, if the distance from the middle of the instrument to the test-types
be either ten, fifteen or twenty feet as marked, set the index m to agree with it;
next, adjust the sliding tube H by means of the hand-wheel so that zero is
indicated on the scale h, then adjust the disc L (which is adjustably secured to the
arbor by screw L 3 for this purpose) until the zero mark on the convex scale is in
juxtaposition with the index L. The patient now applies one eye to be tested to
the eye-piece (the other eye being open but shaded by the shade G', and looks at
the test-letters and lines on the chart, as usual. In testing for optical errors in the
refraction of the eye, the instrument should first be so adjusted (by moving the
hand-wheels) that the effect of a strong enough convex glass is obtained to blur
to the observer all the radiating lines on the astigmatic chart used, and when the
instrument is readjusted so the said blurred lines are clear, the presence or absence
of an optical error in the observing eye is made manifest by the index scale on the
instrument. If the indexes point to zero there is no defect, but if the graduations
on the concave scale are beneath the index, myopia is present in the eye under
examination, and its degree of error is in accordance with the reading on said
scale. If the graduations on the revolving or convex scale should come beneath
its index when the radiating lines on the astigmatic chart are uniformly clear,
hypermetropia is diagnosed, and its degree is in accordance with the reading of the
convex scale.
If in using the instrument some one line or series of lines lying in a given
meridiau on the chart are distinctly seen and others lying at right angles from
them are blurred, astigmatism exists, and its amount is equivalent to the difference
in the refraction of the two chief meridians of the eye as shown by the location of
the clear and blurred lines on the astigmatic chart used.
Astigmatism is also measured, corrected and localized by means of the concave
cylindrical lenses contained in the revolving lens-holders or discs F F in the
revolving eye-piece, as follows;-Adjust the instrument so that the effect of a
strong convex lens be obtained and all the radiating lines on the astigmatic chart
be blurred, then slowly re-adjust until one line or series of lines, lying in a given
plane, become clear, being careful not to go too far,-revolve the eye-piece D so
that the axes of the cylinders in the discs FF' shall come parallel, when exposed,

page_text: with the blurred lines, lying at right angles to the clear lines on the chart, as
described; revolve one or both of the discs F until a cylinder is brought into the
line of vision in the instrument that renders the originally blurred lines clear and
all the lines on the chart are uniformly clear. The eye-piece D may require a
partial revolution to the right or left about its horizontal axis to bring the lines.
uniform during the finding of the suitable cylinder, by the rotation of the discs
containing them, and the pointer a 2 will indicate on the rotating scale the angle of
the astigmatism and by the mark on the edge of the cylinder discs that indicate the
power of the cylinder exposed, the exact amount of astigmatism can be measured
and accurately located in both simple and compound cases.
By reason of the double index on the top of the instrument it can be readily
adjusted at the factory and the optician or user can focus it properly for his range-
or office.
It will be noted that the convex and concave scales are reversed and the degrees.
differ in length, hence the convex scale, which requires the shorter range and the
length of the degrees or units smaller, is on the rotating disc, and the concave scale
on the interior tube H.
The scales indicating dioptrics, it is an easy matter for a physician or an optician
to accurately test a patient's eyes and prescribe the proper glasses necessary to
correct the refractive variations from the normal without the necessity of
employing the expensive and cumbersome cases of test-lenses now generally used
for the purpose.
It is within the knowledge of one skilled in the art and will be understood
therefore that instead of moving the scales of indicating devices for adjustment,.
the indices could be moved, and though I prefer the arrangements shown, I do not
desire to be confined to them.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. In a refractometer the combination with the telescoping tubes and the
objective and lens carried thereby and relatively adjustable each of the tubes
having a scale thereon of the double index secured to one tube and co-operating
with its scale and also co-operating with the scale on the other tube substantially as
described.
+
2. In a refractometer the combination with the telescoping tubes and the
objective and lens carried thereby a scale on one of the tubes and an index on
the other of the arbor for moving the tubes relative to each other and an index
and scale arranged between the arbor and the stationary tube substantially as.
described.
3. In a refractometer the combination with the telescoping tubes and the
objective and lens carried thereby of the rotatable sleeve a movable lens-carrier
thereon having a series of cylindrical lenses arranged to be brought one at a time-
in line with the objective and lens with their axes transversely thereof substantially
as described.
4. In a refractometer the combination with the telescoping tubes and the
objective and lens carried thereby and scales and indices for indicating their
relative adjustment of the rotatable sleeve the two lens-carriers thereon each
having a series of cylindrical lenses and movable to bring the axes of said lenses
transversely of the axis of the objective substantially as described.
5. In a refractometer the combination with the telescoping tubes and the
objective and lens carried thereby of the reversible eye-shade having at one end
the disc and at the other the sleeve extending around one of the tubes and
adjustable thereon independently of the lens substantially as described.
6. In a refractometer the combination with the telescoping tubes and the lens.
and objective carried thereby of the rotatable sleeve two lens-carriers pivoted
thereon each having a series of cylindrical lenses and an aperture therein and an

page_text: index and scale for indicating the rotary adjustment of the sleeve substantially as
described.
7. In a refractometer the combination with the telescoping tubes the lenses
carried thereby and means for adjusting the tubes relative to each other of an
indicator embodying a scale and index and denoting the position of the instrument
relative to a fixed object, and adjustable relative to the frame a second indicator
embodying a scale and index and denoting the relative adjustments of the lenses in
one direction and co-operating with one member of the former indicator and a
third indicator embodying a scale and index and denoting the relative adjustment
of the lenses in the other direction said last-mentioned index and scale being
relatively adjustable irrespective of the relation of the lenses substantially as
described.
8. In a refractometer the combination with the stationary tube having the scale
and the lens therein of the movable tube having a scale thereon the lens therein
the rack and pinion the scale disc adjustably connected to the pinion and its index
and the double index co-operating with the scales on the stationary and movable
tubes substantially as described.
9. In a refractometer the combination with the stationary and movable tubes the
lenses carried thereby and means for adjusting the tubes relatively to each other of
the rotary sleeve having the scale and index the lens-carrier a series of cylindrical
lenses thereon an indicator embodying a scale and index adjustable relative to the
frame a second indicator embodying a scale and index denoting the relative
adjustments of the lenses in one direction and co-operating with one member of the
former indicator and a third indicator embodying a scale and index denoting the
relative adjustments of the lenses in the other direction said last-mentioned index
and scale being relatively adjustable irrespective of the relation of the lenses
substantially as described.
Dated this 3rd day of December 1895
BOULT & WADE,
Agents for the Applicant.