The Gunter Quadrant and Practical Knowledge

The quadrant was a very practical, useful and portable instrument. It also has a projection (a 2-dimensional representation) of the heavens. Understanding the use and construction of the instrument was a way of learning geometry and astronomy. These subjects converged under the general heading of 'dialling', an area of study in its own right that dealt with sundial construction.

A great number of books on dialling were published during the 17th century, when the quadrant was at its most popular. These books primarily deal with the description of the heavens and how celestial co-ordinates are represented on instruments. They also explain the solution of geometrical and trigonometrical problems, which would now be called theoretical, but in the 17th century they were explained and understood practically. For those interesested in dialling knowledge of astronomy and mathematics was never divorced from an understanding of the construction and use of instruments.

Read more: images of projections

Boris Jardine

Boris Jardine, 'A Gunter quadrant and practical knowledge', Explore Whipple Collections, Whipple Museum of the History of Science, University of Cambridge, 2008

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