GB177296A - An improved parallel ruler - Google Patents

Abstract

177,296. Robinson, R. W. Jan. 14, 1921. Rulers; dividing-instruments.-A parallel and section-lining ruler comprises a framework and a movable member which can be measurably displaced in order to determine the distance between successive lines and to facilitate ruling a series of lines at equal distances apart. As shown in Figs. 1, 4, and 5, the frame a has a triangular aperture in which is disposed the wedge-shaped movable member b. The lower edge of the aperture has a scale h coacting with an index b<2> on the member b to indicate the distance between successive lines. The frame also carries a pivoted arm c having a stop e passing through a groove f, an index e<1> on the arm coacting with graduations g. The required adjustment may be obtained either by setting the index b<2> or by setting the arm c and then moving the member b until it abuts against the stop. In the modification shown in Fig. 6, the index b<2> is supplemented by a slidable index b<3> which can be displaced by a, rotatable cam k on the member b; a scale k<1> is marked on the member b around the cam. This ruler may be used to divide a given length into any desired number of equal parts. the arrangement being such that the index b' is displaced by turning the cam so as to give the unit in which the measurement is made, the index being then set opposite a whole number on the scale h. The scale h is replaceable and is held by a spring h<1>. This form of ruler may also be used for columnar shading in which the distance between successive lines is first regularly increased up to a maximum and then regularly decreased. In a further modification the pivoted arm c is replaced by a slidable member on the part b adapted to abut against the part m of the frame.