Ellipsograph

Description:

This ellipsograph is a beautifully engineered drawing device. An oval shape, the ellipse is one of the four conic sections, the others being the circle, the parabola and the hyperbola. Ellipses are important curves used in the mathematical sciences. For example, the planets follow elliptical orbits around the sun. Ellipses are required in surveying, engineering, architectural, and machine drawings for two main reasons. First, any circle viewed at an angle will appear to be an ellipse. Second, ellipses were common architectural elements, often used in ceilings, staircases, and windows, and needed to be rendered accurately in drawings. Several types of drawing devices that produce ellipses, called ellipsographs or elliptographs, were developed and patented in the late 19th and early 20th centuries.

Manufactured by William Ford Stanley and Co. Ltd in the 1880s, this device was designed and patented by English inventor Edward Burslow (often seen as Burstow) in the early 1870s. Burslow lived in Horsham, England, and along with other drawing devices, invented a pentacycle for the Horsham Postal Service in 1882. Though it did not catch on for use elsewhere, the Horsham postal workers wrote Burslow a letter of appreciation for the five-wheeled contrivance.

William Ford Robinson Stanley (1829--1909) was an English inventor and philanthropist with multiple patents in England and the United States. He founded his company, which made precision mathematical and drawing instruments, among other items, in 1854 after a comment by his father about the poor quality of British technical instruments. The company continued to produce drawing and surveying instruments through the 20th century, closing its doors in 1999.

The Stanley/Burslow ellipsograph works on a very different principle than the more common elliptical trammel. Like the H. R. Corkhill ellipsograph in the collection, it uses a series of gears to move five linked arms. As the top arm is rotated, the two main arms with three gears apiece separate into a Y configuration, pulling the bracket below the device along the slot in the main horizontal beam. Into this bracket can be placed two ruled arms of different lengths to produce ellipses varying in size, from 1/4 in by 1/2 in (minor/major axis lengths) to 7 in by 14 in. Interestingly, the ellipses are drawn on a diagonal beneath the device and not in line with it. This allows larger ellipses to be drawn.

This device was transferred to the museum by the Smithsonian Astrophysical Observatory in 1956.

Resources: Great Britain Patent Office, Patents for Inventions: Abridgments of Specifications Period A.D. 1867-76, London: Darling and Son, 1904, p. 48.

William B. Owen, “Stanley, William Ford Robinson,” Dictionary of National Biography, 1912 supplement, pp. 393--394.

British Postal Museum and Archives.