Abstract: A trammel-beam ellipsograph is disclosed wherein the beam is made of two sliding elements in parallel relationship with a scribe-bearing cursor riding upon them. Each beam element is pivotably attached at one end to a slide restrained within one of two perpendicular tracks. A scale on each beam element indicates the distance from the pivot relating to each respective slide to the scribe on the cursor, thereby indicating a measure of the major and minor axes of the ellipse to be scribed. Concentric ellipses having a uniform elliptical annulus therebetween may be drawn by holding the beam elements against sliding while moving the cursor a distance equal to the width of the annulus. The invention further features modular track sections to facilitate drawing ellipses of aspect ratios greater than 2:1. A trammel-beam ellipsograph is disclosed wherein the beam is made of two sliding elements in parallel relationship with a scribe-bearing cursor riding upon them.