William W. Wythes Cyclo-Ellipto-Pantograph Patent Model

This is the patent model for a drawing devices granted U.S. Patent 21,041 to William W. Wythes on July 27, 1858. “Be it known that I, WILLIAM WYTHES, of the city of Philadelphia and State of Pennsylvania, have invented a new and Improved Instrument for Drawing and Copying.” (U.S. Patent Application). The Smithsonian also owns a patent model by Wythes for a cloth-measuring machine (U.S. Patent 18313). (The original patent drawings and descriptions can be viewed at Google Patents.) Special about this patent model is that the inventor has engraved “Wm W Wythes, inventor” on the large brass disc on the model.

Wythes was awarded a degree in medicine from Philadelphia College of Medicine in July 1851. He served as an assistant surgeon in the U.S. Volunteers, part of the Union forces, during the Civil War and was singled out in the Official Records of the Union and Confederate Armies, 1861--1865, as having been a notable member of the Asylum General Hospital in Knoxville during the war.

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.

The inventor claimed that the device could draw not only ellipses, but also epicycloids and spirals, thus the “cylco" in the title of the model. An epicycloid is the curve traced by a point on the circumference of a circle as it rolls about another circle. (See Schilling models 1982.0795.01, 1982.0795.02, 1982.0795.03, and 1982.0795.05 in the National Museum of American History collection.) As the name also implies, this device could be used as a pantograph, a mechanical devices used to copy line drawings. As the original drawing is traced, the pencil attached to the opposite end of the devices produces, through a series of linkages, a copy. The copy can also be scaled up or down in size. One common application of a pantograph (before the advent of computers) was to reduce the size of a drawing for use in minting money. For example, the original line drawings found on U.S. bills were full-size drawings. They were reduced and etched in order to be printed. Pantographs were also used, notably by Thomas Jefferson, for making a copy of a letter as the final draft of the original was being written out.

The Wythes Cyclo-Ellipto-Pantograph consists of a wooden beam of 38 cm (15 in) long. At one end is a large vertical brass disc with gear teeth on the back. This gear turns a horizontal disc that is attached to a brass beam under the device. There are two movable pieces along the beam. One is the pivot point of the device, under the wooden handle. The other is the writing point below the horizontal brass disc placed along the beam. As the large disc at the end of the beam is turned, the gears cause a chain (similar to a miniature bicycle chain) to circulate along the length of the beam. As the long brass beam beneath the device turns, the smaller brass beam below the movable disc traces a similar shape. By adjusting the location of the pivot point and the small horizontal disc, various shapes are formed. However, it is not clear that all the claims of the inventor are warranted. It appears that only portions of curves or ellipses can be generated. The device was offered in the J. W. Queen “Illustrated Catalogue” of 1859.

Resources:

Announcement of the Philadelphia College of Medicine, for the Collegiate Year, 1854-5, (Philadelphia: King and Baird, 1854), 13.

Official Records of the Union and Confederate Armies, 1861-1865, (Washington, D.C.: National Archives, Microcopy 262, 1959), 537.

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