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Robert Recorde and the Whetstone of Witte

Collections - Posted 31-05-2021

Robert Recorde, who was born in Tenby is renowned for being the first mathematician to use the “=” symbol in a published book. This was featured in the The Whetstone of Witte which the Library will be exhibiting on-line soon.

Robert Recorde was born in Tenby in 1512. His mother was from Machynlleth. It was in Tenby that his interest in mathematics was first realised and this was recognised by the London Mathematical Society in 2015 when it commissioned an exhibition in his hometown to coincide with the 150th anniversary of the founding of the Society.

Recorde clearly thought it was important to provide mathematical education to the masses who were not familiar with Latin or Greek. Most scientific books of the time were written in Latin and Recorde was one of the first authors to write mathematical books in English.

The first equation which used the symbol “=” can be seen in the illustration (it is on page 236 of the Library’s digital copy) from The Whetstone of Witte. There were other symbols used by mathematicians of the time in Europe which could easily have been adopted, and it was nearly a century before the two lines were generally accepted and recognised to denote equality. The symbol was used in influential works such as Richard Norwood’s Trigonometric, and its use then spread from England to Europe and to the rest of the world. To explain his use of two parallel lines, Recorde writes that “To avoid the tedious repetition of these words – is equal to – I will set as I do often in work use, a pair of parallels or Gemowe lines of one length, thus: = because no two things are more equal (see relevant page from the book blow).”

Recorde was also among the first mathematicians to use the forms of numbers that we are familiar with today (1, 2, 3, etc.). In another of his books named The Groundes of Artes, Recorde compares these numbers with the Roman numerals that were commonly used in textbooks at the time (i, ii, iii). The form of numbers that are used today are derived from Hindu or Arabic numbers from around 600 A.D. It is quite fascinating to see that Recorde had to introduce these numbers to his lay readership. This shows that English scientific writing involving mathematics and arithmetic was in its infancy and that Recorde was a key figure in its introduction to the people of Britain.

 

 

Recorde was a Fellow in All Souls’ College, Oxford having earlier graduated in mathematics. He later studied medicine at Cambridge. He was also a Royal Physician and was appointed Head of the Royal Mint. While working at the Mint he was answerable to the Earl of Pembroke. Recorde accused the Earl of siphoning some of the profits of the Mints to himself. He was prosecuted for slander for making the accusation and was fined a thousand pounds. As he had no means to pay the fine he was imprisoned for bankruptcy. He soon fell ill in prison and died in 1558. When Elizabeth I rose to the throne a few years later the case was re-opened and his name was cleared. As compensation, land was given to the family in Tenby.

Recorde wrote his mathematics in English so that it could be understood by people. He introduced the numbers 1, 2, 3 etc. to his readers. But we remember him mainly for being the first mathematician to use two parallel lines to denote equality. Robert Recorde made an unique contribution to mathematics in the sixteenth century.

Bibliography

Roberts, G. (2016) Robert Recorde: Tudor Scholar and Mathematician, Cardiff: University of Wales Press.

Roberts, G. Ff. (2020) Cyfri’n Cewri: Hanes mawrion ein mathemateg, Caerdydd: Gwasg Prifysgol Cymru.

 

Hywel Lloyd,

Assistant Librarian.

This post is also available in: Welsh

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A blog about the work and collections of the National Library of Wales.

Due to the more personal nature of blogs it is the Library's policy to publish postings in the original language only. An equal number of blog posts are published in both Welsh and English, but they are not the same postings. For a translation of the blog readers may wish to try facilities such as Google Translate.

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