IMPROVEMENTS IN TRANSPARENT SCALES AND PROTRACTORS
Year: 1884

page_text: WC, HENRY EDWARD THOMAS and JACOB CHRISTY SHRADER, of the City and
County of San Francisco State of California, one of the United States of America
Gentlemen do hereby declare the nature of our Invention for IMPROVEMENTS IN
TRANSPARENT SCALES AND PROTRACTORS" and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
Our Invention relates to a transparent ruler and scale of peculiar construction,
and in combination with it of an inverted protractor formed within the same ruler,
the relation of the different graduations being such that any series of parallel or
other lines may be marked by the aid of this scale, and the relative position,
distances, or angles, determined and indicated at once without the employment of
other instruments.
Referring to the accompanying Drawings for a more complete explanation of our
Invention:
Figure 1, is a plan view of our instrument.
Figure 2, is an end view.
Figure 3, is a perspective view.
Let A, represent a ruler which may be made of glass or other transparent
substance. This ruler is made of considerable thickness and the line or graduations
are marked upon the side which is in all cases laid upon the paper, so that
they will be in exact contact with the paper, and the measurements and lines can
be accurately obtained.
One or both longitudinal edges of this, ruler are marked with a graduated
scale in the ordinary manner of graduating the edge of a ruler, so that lines of
any given length can be drawn along these edges, and the length at once indicated
by the marks.
Transversely across the ruler at equal distances apart are lines b across the
entire width of the ruler..
These lines can be made by extending the inch marks of the edge scale across
the ruler, thus dividing the ruler into as inany parts as there are transverse lines.
Each transverse line b then forms a basis for a separate graduated scale across
the width of the ruler. This latter scale is formed by making short lines c across
the lines b and parallel with the edge of the ruler.

page_text: These lines are also graduated so that the marks indicating the inch, and the
marks indicating the fraction of an inch are casily distinguishable by their length
in the usual way.
These lines enable us to make lines parallel with the edge of the ruler over a
line that has already been drawn, until the cross line which indicates its distance
from the next line corresponds with it.
Another line is then drawn by the edge of the ruler, thus forming the two lines
at the required distance apart.
The transverse lines b aid in determining the relative position and distance
apart of the terminals of the two lines.
That is: If the line already drawn is only one inch in length, and it is desired
to make another line of equal length parallel with it, but one inch in advance of it,
and one inch to the right of it, the cross lines c determine the distance apart of the
planes of the two lines, while the transverse lines-c-determine the relative position
of their terminals.
At some point in the length of the ruler, and preferably at its middle, is made
a semi-circle e the curve of which is reverse to the edge from which the anglo is to
be laid off, and this semi-circle marks off with radial lines f.
The figures indicating the degree of each-angle-can also be indicated opposite each
radial line. By this device geometrical-figures-can--be-drawn--with-mathematical_
precision.
The ruler is transparent so that the lines already drawn can be easily scen
through it, while the lines and scale marks are also distinguishable so that they
can-be-compared with, adjusted to, and placed upon the lines already drawn.
By means of the protractor combined with the edge-scale-of-the-ruler,-lines-of-a-
given-length may be-at-once-drawn at any desired angle to a given line.
For instance, given a straight line, now to produce a line say one inch in
length-at an angle-of-twenty-degrees to the given line, place the radial line of the
protractor which indicates twenty degrees, upon the given straight line..
This disposes the straight edge of the ruler so that it indicates the angle of
twenty degrees to the given line. Now as the edge of the ruler is graduated
to a scale, a line may be produced of any desired length, at any distance from
the given line.
This result has never before been produced in a single ruler.
It has always
required the use of a protractor and ruler separately; but by combining the two in
a transparent ruler as shown, that is, the reversed protractor and the edge scale of
the ruler, we can lay off work and mark it out at the same time.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed wo declare that what
we claim is
A transparent ruler having a graduated edge scale, and provided with transverse
division lines b which extend entirely across the width of the ruler, each of which
bas graduated cross lines c made across it, said ruler being provided with a
circular inverted protractor-scale e, with radial lines f, substantially as above
described.