Abstract: A new geometric instrument-compass for a practical use that allows the trisection of an arbitrary angle as well as retains its effective functionality for operations that can be performed by the conventional compass is disclosed. The design proposed makes this new compass universal in terms of its applicability, namely, it can be used in a vertical position as the conventional compass (depending on the purpose or convenience of the user) and can be used in horizontal position (if it is required to perform the trisection of an angle or even some other operations generally performed by the conventional compass). The simplicity of the design and effectiveness of operations makes this instrument an attractive tool for practical application.

Abstract: An angle trisecting device with a base section having two angle indicating scales and an elongated member with a straight edge portion. The elongated member is pivotally mounted on the base section. A given angle on one angle indicating scale coinciding with the straight edge portion corresponds to a trisected angle on the other angle indicating scale coinciding with the straight edge portion. Pivot pins extend from the elongated member and are removably captured in respective base slots to ensure reliable operation. In another embodiment a guide wall extends from the base to ensure reliable operation. An optional link arm is pivotally mounted to the base section and with one end pivotally mounted to the elongated member.

Abstract: An instrument for trisecting an angle has two circular plates and four pointers. Two pointers are to define a given angle which can be an acute angle or obtuse angle. Two other pointers are to divide the given angle into three equal angles when they are perpendicular each other.

Abstract: A simple drawing instrument for the subdivision of angles into halves, thirds and fifths comprises two planar pieces connected at a pivot point. Each piece has three curved edges, being the external edge of the part and the two edges of a curved slot within the part. The pieces can be rotated within their planes relative to each other. The instrument is operated by placing the axis of the pivot at the apex of the given angle, and positioning the reference markings on the two parts so they lie along the sides of the angle. The intersections of various curved edges of the two parts define the points that subdivide the angle into halves, thirds and fifths.

Abstract: Device for dividing an angle into equal or proportional parts, comprising the surface flattened or not of a right cone, of which the axis is adjustable through the vertex of the angle, on which surface a describing line and a number of lines corresponding to the number of angles into which the angle has to be divided, are or can be provided such that they all pass through a point on said describing line and divide into equal or proportional parts the circular arcs constituted by the planes perpendicular to the cone axis and the surface and lying between the intersection points of these circular arcs and the line most remote from said describing line.