Goniometer, reflecting, Wollaston type with weight

Written for Brought to Light by Emily Kennedy. Research Group: Bessie Ng, Amy Rees, Anne Fleuren, Emily Kennedy.

Wollaston type goniometer (brass and blackened brass) with mirror attachment, engraved silvered scale and vernier read-out with twin adjusting wheels and fine adjustment, made by Troughton & Simms, with balance/counterweight by L.Oertling Ltd.

This object is a geological measuring instrument known as a goniometer. Created during the nineteenth century, its design, referred to as the Wollaston goniometer, was developed by William Hyde Wollaston, an English chemist and mineralogist. Strong and inexpensive, the Wollaston goniometer held the capacity to be developed into a greater tool through its ability to support accessory parts. Such an adaption of Wollaston’s base can be seen on this particular goniometer. On top of the foundation built by Troughton & Simms, an additional device, manufactured by L.Oertling, has also been added, as well as a mirror.

The goniometer was primarily used in crystallography to measure the angles between faces on the surface of a crystal. To achieve this; the crystal would be fastened between two screws, or held in place by wax, before being rotated. An external light was then shone on the faces at different angles. By measuring this light, the angle between the faces could be calculated.

Troughton & Simms was a London company who built scientific instruments. Established in 1826 by Edward Troughton and William Simms, the business evolved into a ‘hub’ for the development of scientific tools. In an 1830 catalogue, Troughton & Simms listed the Wollaston goniometer for three pounds and three shillings.

Like Troughton & Simms, L. Oertling was also a London based company. It was founded by Ludwig Oertling in 1847, a German instrument maker who migrated to England in 1844. Whilst it is clear that Oertling’s device was attached to this goniometer as some sort of accessory, its exact function is unknown. Due to the nature of Oertling’s work (he focused on balances), it can be deduced that this instrument acted as a possible leveling device, enhanced by the presence of spirit levels along its outer edges. However, further research would be needed if its specific use is to be determined.

Throughout the nineteenth century, the goniometer was one of the most important instruments of crystallography. With the arrival of the twentieth century, Wollaston’s goniometer significantly influenced the formation of x-ray diffraction technology, which marked the next phase of crystal science.

Father and son scientists William and Lawrence Bragg, the former a lecturer and the latter a graduate, both from the University of Adelaide, were pioneers in this then-emerging field. The duo were awarded a joint Nobel Prize in 1915 for their contributions to x-ray crystallography, an achievement that perhaps would not have been possible without Wollaston’s goniometer.