Maker's Name: 
Troughton & Simms, London
Where made: 
25 × 14.5 × 19.5 cm

This object is a goniometer, made by Troughton & Simms around 1880. Its design is based on the goniometer developed by English chemist and mineralogist William Hyde Wollaston (1766-1828). Wollaston is famous for discovering two chemical elements, palladium and rhodium as well as developing a method for processing platinum. A goniometer is used to measure angles or to rotate an object to a precise angular position. In crystallography goniometers are used to measure the angle between crystal surfaces. They are also used to rotate crystal samples precisely for X-ray diffraction experiments.

This goniometer measures the angles between faces on crystals by using the light reflected from the faces. It was important to the accuracy of crystallography experiments that the user know what the angles between each face of a single crystal were. The crystal would be held between the two screws so that it could be rotated around the horizontal axis. The crystal was sometimes held in place by a makeshift cement, comprised of a mix of beeswax and pitch. This axis was connected to a graduated circle The crystal was then rotated so that the edge between the two faces of interest was parallel to the axis of rotation of the graduated circle. A distant source of light was then directed on the faces at various angles. By measuring the light the angle between the faces could be determined. This instrument can make measurements to 1’ arc. While this device was portable, accurate and easy to use it could only measure the angle between two faces at a time. If the user wanted to measure the angles between each set of adjacent faces they would have to remove the crystal, reposition it and start again. This difficulty was overcome with the development of the two circle goniometer

Troughton & Simms was a scientific instrument making business founded in London in 1826 by Edward Troughton and William Simms. Located on Fleet Street the shop became one of the finest scientific instrument manufacturers in London. At the time there was a high demand for precision instruments for areas such as astronomy and surveying. Though the firm was known for their quality they could sometimes take years to deliver their instruments, frustrating their customers. In 1834 the Houses of Parliament were burnt to the ground, along with the official standard measurements, the standard yard and the standard pound. Troughton & Simms were commissioned to create new standard measurements. The process took 10 years of testing and research. In 1922 Troughton & Simms merged with Cooke and Sons, another scientific instrument manufacturer to create Cooke, Troughton and Simms. During the First World War the company expanded production and began to produce military instruments. The company still exists today under the name Cooke Optics Ltd and produces camera lenses.

This item is part of the UQ Physics Museum Crystallography Tour
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