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Model of Conical Refraction

A plaster mathematical model composed of curved and flat surfaces. Lines and curves are moulded into its surface and highlighted in black. The model is labelled in French with additional English annotation written onto the surface in pencil.

Accession Number:

Alternative Name:

Geometric Model, Wave Surfaces for Refraction in a Negative Biaxial Crystal

Primary Materials: Plaster


The original French engraved markings are generally legible and may have been retraced. Additional English annotations have been added in pencil.

Dimensions (cm): Height=11, Width=15.5, Length=11


This is a mathematical teaching model used to demonstrate the principles


Edges of the model are chipped and work. Surfaces are worn and scuffed. There are some small stains, especially on the flat bottom surface. At least one of its markings is illegible.

Associated Instruments:

Manufacturer: J. G. Hofmann, Paris.

Date of Manufacture: Mid-to-late 19th century.


This artifact was gathered from the office of Professor Boris P. Stoicheff at the University of Toronto Department of Physics by Professor Stephen W. Morris following Stoicheff’s death in 2010.
It was transferred by Professor Morris to the IHPST on 17 August 2021.

Additional Information and References:

Lunney, James G., and Denis Weaire. “The Ins and Outs of Conical Refraction.” Europhysics News 37, no. 3 (2006): 26–29.

J G O’Hara. “The Prediction and Discovery of Conical Refraction by William Rowan Hamilton and Humphrey Lloyd (1832-1833).” Proceedings of the Royal Irish Academy. Section A: Mathematical and Physical Sciences 82A, no. 2 (1982): 231–57.

This model is represented in the online catalogues of the Rijksmuseum Boerhaave, the National Museum of American History, and possibly others.

Historical Notes:

This is a plaster mathematical model representing conical refraction, an unusual phenomenon in which a ray of light emerges from a birefringent crystal as a ring, a section of a hollow cone.

The model represents an early instance of a predicted phenomenon confirmed through experiment. In October of 1832, the Irish mathematician and astronomer William Rowan Hamilton (1805-1865) described the phenomenon mathematically. The effect was first observed in 1833 by the Irish physicist Humphrey Lloyd (1800–1881) using an aragonite crystal. This was a challenging experiment because it required a birefringent crystal of unusual optical clarity.

  • Donated to UTSIC