Maker's Name: 
Stoe & Cie GmbH, Heidelberg
Where made: 
39 × 26 × 31 cm

This object is a two circle Goniometer, made in Germany by Stoe & Cie. In the field of Crystallography goniometers are used to measure the angles between faces of crystal samples. When studying crystals it is important to be able to accurately know the angles between faces. The Wollaston Goniometer, which is also on this tour, can very accurately measure these angles but can only do one at a time. In order to measure another the crystal must be removed and reset. This process is laborious and time consuming and so goniometers like this two circle one were invented so that scientists could measure multiple angles (or zones) without resetting the crystal.

To operate this goniometer, the user would fix a small crystal to the stand that is held at the center by the right arm. In the past melted wax or similar substances were used, however today blue-tac is a popular choice. Once the crystal was in the desired position a strong, narrow beam of light would be shone through the crystal from the collimator (the lower of the two arms). The user would then look through the telescope (the upper arm) and line up the light reflected off the crystal with the crystal itself. When the images were lined up the user would note the positions of the vertical and horizontal graduated circles. These two graduated circles are what give the goniometer its name. The two numbers then acted like a longitude and latitude for describing the position of the crystal face. When the user wanted to look at the next face, they simply rotated the crystal using the rotatable arm.

Stoe & Cie was founded in 1887 in Heidelberg by Peter Stoe. The company specialised in the design and production of one and two circle goniometers. During the 20th century Stoe & Cie were instrumental in the development and improvement of goniometers. The company still exists today, specialising in the non-destructive analysis of substances. They provide high quality instruments, such as diffractometers to universities and laboratories around the world.

This goniometer was used in the former UQ Chemistry Department.

This item is part of the UQ Physics Museum Crystallography Tour
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