Calculating device, called Arithmeticall Jewell

This calculating device called the 'Arithmeticall Jewell' permitted addition, subtraction, multiplication and division to be undertaken without use of pen and paper. It was designed by William Pratt in 1616.

The device comprises two ivory faced wooden tablets. One (below in the picture) has 14 columns, each with small brass parallel sectors. The other has seven pairs of columns for laying out 'astronomical fractions' to the base 60.

In England at this time the new form of ciphering with Hindu-Arabic numerals had largely, but only recently, replaced the traditional manual arithmetic done with counters on a counting board, with the results recorded in ledgers in Roman numerals.

Record details

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Online ID:	000-100-102-829-C
Image Rights Holder:	National Museums Scotland
Project:	0098: National Museums Scotland Project description \| View all records in project
Ref:	National Museums Scotland T.1985.114
Date:	Around 1616 c. 1616
Material:	Wood, ivory
Dimensions:	122 mm x 65 mm x 5 mm (each tablet)
What:	Arithmeticall Jewell / perpetual pro-forma / tablet
Subject:
Who:	William Pratt (Maker)
Where:
Event:
Description:	Arithmeticall Jewell, consisting of two wooden tablets, perpetual pro-forma for undertaking arithmetic procedures, designed by William Pratt, c. 1616
References:	Bryden, D. J., 'The Arithmeticall Jewell or Jewell of Arithmetick' in Quanto: Abbot Hall Art Gallery, Kendall Quarterly Bulletin 23, no 2 (1985), pp 9-14
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