IMPROVE- MENTS IN INSTRUMENTS FOR MEASURING ANGLES
Year: 1884

page_text: 23
I HENRY SAMUEL SPILLER WATKIN of Highbridge Street Waltham Abbey in
the County of Essex do hereby declare the nature of my invention for IMPROVE-
MENTS IN INSTRUMENTS FOR MEASURING ANGLES and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :—
The improvements consist in the application of curved mirrors to the measure-
ment of angles (vertical or horizontal).
The application of my invention to various purposes is shown in the accompanying
Drawings of which the following is a description.
Figure 1 shews one application of my invention to the measurement of vertical
angles.
In the Drawing the cover of the instrument is supposed to be removed.
A B C is a plumb bob which is pivotted at M. A B is a curved mirror of such a
radius às to focus and form a distinct image of a scale at E. GEF is a scale of
degrees (calculated to double the radius E M). H is a small opening, with or
without a pointer, through which objects can be seen by direct vision by the eye
placed at E. The eye at E also sees the magnified reflection of the scale. The
plumb bob A B C being. properly adjusted by means of the screw D the angle of
elevation or depression subtended by any object can be at once ascertained. By
the use of a base piece or stand as is shown in Figure 4 the inclination of surfaces
can in like manner be determined.
Figure 2 shows another form of the invention with the cover removed. In this
case the plumb bob consists of a piece A B C having a weight O attached and
pivotted at M. The scale of degrees E F G (calculated to the radius E M) is fixed
to the edge of the piece A B C. An opening H and eye hole at E are provided
as before through which objects by direct vision can be viewed.
Figure 3 shows the last described instrument complete with its cover. A brass
piece I is secured to the cover by screws working in a slot I-at the end of this
brass piece I facing the eye hole E is placed a curved mirror A' B' which gives a
magnified reflection of the scale. Fixed to the inner portion of the box near the
eye hole E is a piece of ivory or other material K with a single line or zone
engraved or otherwise marked upon it. A magnified image of this line is also seen
by the eye at E. By bringing the image of the line opposite any object viewed

page_text: through the opening H and reading the scale the angle of inclination of the object
is determined.
Figure 4 represents another form of the invention in which the moveable
piece A B C is a continuous cylinder as no cock piece is employed to support the
pivot one end of the pivot is caused to work in the base plate the other in the
cover.
Figure 5 shows another modification of my invention in which the reflecting
mirror is fixed at A² B².
I do not confine myself to the dimensions given in the Drawings as the instru-
ment can be constructed of any size. The scale may also consist of heights or
distances instead of degrees.
Figure 6 shews the application of my invention to the measurement of horizontal
angles.
A B C is the moveable disc to which is attached a magnetic needle pivotted in
the usual way. A curved mirror fixed to the cover in a similar manner to that
shown in Figure 3 allows of the reading of degrees or other indications on the
edge of the moveable disc.
Thus the eye at E is enabled to read the deviation from the magnetic meridian
of any object viewed through the opening H, the fixed zone line being placed in
the inside of the outer case as described with respect to Figure 3.
The dip of the magnetic needle could also then be viewed by suitably
pivotting the moveable disc A B C. The position of the curved mirror may be
varied.
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,
1. The application of curved mirrors to instruments for measuring angles
substantially as herein shown and described. and,
2. The application of curved mirrors to instruments for measuring horizontal
angles with or without the application of a magnetic needle substantially as herein
shown and described.
D dare of January 198
Dated this First day of January 1924.
H. S. S. WATKIN.
By Harris & Mills,
Agents,
23 Southampton Buildings,
London.