GB191005753A - A Stencil for use of Students of Conic Sections and other Branches of Mathematics. - Google Patents

Abstract

5753. Dufton, J. T. March 8. Templets. - A stencil for drawing conic curves consists of a thin plate, preferably of transparent material such as celluloid, from which a r e cut pieces having conic curces as outline. The foci, latera recta, and other related points and lines are indicated on the stencil. The Figure shows one arrangement o f the curves. The curve A is a rectangular hyperbola, the asymptotes of which are obtained by producing the sides a, b of the stencil. The cut-out B is bounded by one branch of an oblique hyperbola K and its conjugate hyperbola L and one of their asymptotes, the other asymptote being obtained by joining the point f to the centre c. Two ellipses D, E have their minor axes in the line c c<1>, and their latera recta in the lines k, k<1>, l, l<1> coincident with the latera recta of the hyperbola K, so that by suitably placing the tracings of the ellipses and hyperbola on paper confocal conic curves are obtained. The directrices of the ellipse D coincide with the edges of the stencil, and those of the ellipse E are given by the lines m, m<1>. The cut-out F is bounded by two parabolas G, H having their axes in the line c c<1> and their directrices in the line n n<1> and in the bottom edge of the stencil respectively. The latera recta are given by the lines p p<1>, n n<1> respectively.