A New or Improved Astigmatic Test Chart or Instrument for Testing Sight.
Year: 1898

page_text: Date of Application, 1st Sept., 1898
Complete Specification Left, 31st May, 1899-Accepted, 1st July, 1899
A New or Improved Astigmatic Test Chart or Instrument for
Testing Sight.
1, ERNEST BEAUMONT, of 79, Lidgit Street, Lindley, near Huddersfield, in the
County of York, Optician, do hereby declare the nature of this invention to be
as follows:-
This invention has reference to a new or improved astigmatic test chart or
instrument, which at a glance indicates the meridian for axes of cylindrical lenses
without any calculations as is the case with the charts at present in use.
My improved chart comprises a circular or other suitable form of disc, divided
into radiating degrees, being numbered around an outer circle. There is an inner
circle, and opposite the degree numbers on the outer circle are placed in plain
or coloured figures, the same number as the one at right angles to it; thus if the
degree number on the outer circle be 90°, the one on the inner circle will be 180°,
if 40°, it will be 130°, if 50° it will be 60° and so on.
The chart has a revolving centre piece made in the form of a square, which is
divided into four smaller squares. These four squares are divided by black lines,
forming 45°, 90°, 135°, 180° with the horizontal angle points as shewn in the
accompanying diagram, where A is the stationary disc, B the revolving centre
piece rotating upon fulcrum C.
When the lines on the square to which the pointer D is fixed appear the blackest,
the number in the inner circle to which the indicator D points will shew the degree
number on the chart at which the axis of the cylinder should be placed.
The numbers on the chart can be arranged to correspond with any kind of chart
notation.
A New or Improved Astigmatic Test Chart or Instrument for
Testing Sight.
I, ERNEST BEAUMONT, of 79, Lidget Street, Lindley, near Huddersfield, in the
County of York, Optician, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
-
This invention has reference to a new or improved astigmatic test chart or

page_text: instrument, which at a glance indicates the meridian for axes of cylindrical lenses
without any calculations as is the case with the charts at present in use.
My improved chart comprises a circular or other suitable form of disc, divided
into radiating degrees, and numbered around an outer circle. There is an inner
circle, and opposite the degree numbers on the outer circle are placed in plain
or colored figures, the same number as the one at right angles to it; thus if the
degree number on the outer circle be 90° the one on the inner circle will be 180°,
if 40°, it will be 130°, if 150° it will be 60° and so on.
The chart has a revolving centre piece made in the form of a square, which is
divided into four smaller squares. These four squares are divided by black lines,
forming 45°, 90°, 135°, 180°, with the horizontal angle points as shewn in the
accompanying diagram, where A is the stationary disc, B the revolving centre
piece rotating upon fulcrum C.
When the lines on the square to which the pointer D) is fixed appear the blackest,
the number in the inner circle to which the indicator D points will shew the degree
number on the trial frame at which the axis of the cylinder should be placed.
The numbers on the chart can be arranged to correspond with any kind of trial
frame notation.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
An astigmatic test chart for testing sight, marked and graduated as herein shewn
and described in combination with a graduated revolving square B.
both day of
TASKER & CROSSLEY,
Patent Agents, Halifax, Agents for Applicant.
TASKER & CROSSLEY,
Patent Agents, Halifax, Agents for Applicant.