a PARALLEL RULER
Year: 1884

page_text: PROVISIONAL
DRECIFICATION,
"
I DONALD POPE of 130 Drumond St. N.W. in the county of Middlesex
Engineer do hereby declare the nature of the said invention for a PARALLEL
RULER" to be as follows:-
In this ruler guides are employed, fixed to one bar of the rule and sliding in
grooves or recesses in the other. In place of the usual link double liuks are
employed and nuts may be placed at the central joints to receive a rod scrowed
right and left at the opposite ends with a milled head in the centre to turn it by.
By this means the links are moved to or from each other by the turning of the
screw and the bars of the ruler closed up or opened out. The guide bars may be
marked on the four edges with scales or may be so graduated that line shading may
be accurately accomplished or cross sectioning may be regularly and neatly done by
using any of the scales to suit the size of drawing The total travel is more than
double that which could be obtained with a ruler of the same length on the old
principle with single lovers instead of compound ones, at the same time the movable
ruler travels always at right angles to its edge whereas the old style travels at au
angle of 45° to its edge.
There are various ways of working them besides the right and left hand scrow
which of course may be any pitch but the finer the pitch the steadier it would
be as the locking action would be greater and the ruler could be adjusted more
accurately however for rougher work one or more springs or strong elastic band
might be used instead of the screwed rod. These rulers may also be made with the
links to fall in the same direction and connected by a rigid bar or other suitable
means.
Where required the stationary bar of the rule is made with a recess on its
underside and a ring of india rubber let in round the edges and when placed upon
the board the air can either be extracted through a suitable valve so as to form
a partial vacuum in the recess or an automatic valve may be used to allow the air
to escape as the ruler is pressed upon the board and prevent its return: or the
valve may be dispensed with and the rule simply pressed upon the board; or
a clamp may be used. The object being to fix the rule to the board so that the
hands may be free to work with.
"

page_text: Figure 4 is an end view.
In this ruler guide, bars B are employed, fixed to one ruler bar A of the rule and
sliding in grooves or recesses in the other ruler bar A' In place of the usual link,
double links C are employed and nuts E may be placed at the central joints e to
receive a rod D screwed right and left at the opposite ends with a milled head Di
in the centre to turn it by. By this means the links C which are arranged in pairs
as shown are moved to or from each other by the turning of the scrow and the
ruler bars A. A' closed up or opened out. The guide bars B may be marked on the
four edges with scales, or may be so graduated that line shading may be accurately
accomplished, or cross sectioning may be regularly and neatly done by using any
of the scales to suit the size of drawing. The total travel is more than double that
which could be obtained with a ruler of the same length on the old principle with
single levers instead of compound ones, at the same time the movable rule travels
always at right angles to its edge, whereas the old style travels at an angle of 45°
to its edge. There are various ways of working them besides the right and left
hand screw, which of course may be any pitch, but the finer the pitch the steadier
it would be, as the locking action would be greater and the ruler could be adjusted
more accurately, however for rougher work one or more springs, or strong elastic
bands might be used instead of the screwed rod.
Where required the stationary bar of the rule is made with a recess on its under
side and a ring of india rubbor let in round the edges and when placed upon the
board, the air can either be extracted through a suitable valve, so as to form
a partial vacuum in the recess, or an automatic valve may be used to allow the air
to escape as the ruler is pressed upon the board and prevent its return, or the valve
may be dispensed with and the rule simply pressed upon the board, or a clamp may
be used, the object being to fix one bar of the rule to the board, so that the hands
may be free to work with.
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
First. In a parallel ruler the combination with the ruler bars A A¹ of links C
arranged in pairs the free ends of each pair being jointed together and carrying
a nut E which traverses the right and left screw threaded rod D in such manner
that by revolving rod D they are caused to approach or recede from each other and
so draw together or separate the bars A Aª substantially as specified,

page_text: Second. In a parallel ruler the combination with the ruler bars A A¹ of links C
arranged in pairs with their free ends jointed together as at e the movement of the
bars A A¹ being accomplished by bringing the joints e nearer to or farther from
- each other.
Fourth-In a parallel ruler the combination with the ruler bars A A¹ of guide
bars B secured to one of the ruler bars and free to move in or upon the other
substantially as set forth.