The Tudor Society

18 June – Robert Recorde, his urinal and the equals sign

Yes, you read that title right! On this day in Tudor history, 18th June 1558, the will of Welsh mathematician, physician and mint administrator Robert Recorde was proved.

Recorde invented the "=" sign and wrote books on mathematics and also a urological treatise "The Urinal of Physick".

Let me tell you all about this man and his works, which have such catchy titles!

Also on this day in Tudor history, 18th June 1546, twenty-five-year-old Anne Askew was found guilty of heresy at London’s Guildhall along with Nicholas Shaxton (former Bishop of Salisbury), Nicholas White and John Hadlam. Find out more about what led to the trial and execution of this Protestant martyr in last year’s video:

Links to read Robert Recorde's works:

The Whetstone of Witte - https://archive.org/details/TheWhetstoneOfWitte
The Grounde of Artes - https://www.maa.org/press/periodicals/convergence/mathematical-treasures-the-grounde-of-artes-by-robert-recorde
The Urinal of Physick - https://books.google.es/books/about/The_urinal_of_physick.html?id=Sax491XagIgC&redir_esc=y

Also on this day in history:

  • 1529 – Catherine of Aragon makes her first appearance at the Legatine Court at Blackfriars.
  • 1588 – Death of Robert Crowley, Protestant printer, author, poet and Church of England clergyman. He was buried in the chancel of St Giles Cripplegate under the same stone as his great friend martyrologist, John Foxe.
  • 1592 – Death of Francis Wyndham, Judge, at the Committee House, St Peter Mancroft, Norwich. His trials included the treason trials of John Somerville and William Parry in the 1580s, and his legal knowledge led to him being approached for advice on Mary, Queen of Scots.
  • 1616 – Death of Thomas Bilson, Bishop of Winchester, at Westminster. He was buried at Westminster Abbey.


On this day in Tudor history, 18th June 1558, Welsh mathematician, physician and mint administrator Robert Recorde’s will was proved. His date of death is not known, but is thought to have been mid-June 1558.

Robert Recorde was born in around 1512, in the reign of King Henry VIII. He was the second son of Thomas Recorde of Tenby, Pembrokeshire, in Wales, and his wife, Rose. Recorde graduated with a Bachelor of Arts from Oxford in 1531, and, in the same year, became a fellow at All Souls College, Oxford. He is thought to have taught Mathematics before studying medicine at Cambridge University, where he received his MD in 1545.

Record wrote “The Urinal of Physick” (I do love that title), a urological treatise, and had it published by Reynolde Wolfe in 1547. He also wrote a book on anatomy.

In King Edward VI’s reign, Recorde served as a mint administrator, acting as comptroller of the Bristol Mint in 1549 and also the mint at Durham House, in London. In 1551, he was appointed as surveyor of the mines and moneys in Ireland, but was recalled to England in 1553.

Robert Recorde is known for introducing the “equal to” sign, "=".

He published several mathematical works, including “The Grounde of Artes, teachings the Worke and Practise, of Arithmeticke, both in whole numbers and fractions” in 1543 – catchy title! - which was the first book on Algebra published in England. He also wrote a book with another catchy title, “The Whetstone of Witte, whiche is the seconde parte of Arithmeteke: containing the extraction of rootes; the cossike practise, with the rule of equation; and the workes of Surde Nombers”. It was in that book that he introduced the "=" sign.

In the description to this video, I will share a link to read The Whetstone of Witte online, and also a link to see images and information of “The Grounde of Artes. Google Books has his treatise “The Urinal of Physick”.

If you want to read more about Recorde himself, the book Robert Recorde: The Life and Times of a Tudor Mathematician edited by Gareth Roberts and Fenny Smith looks good, as does Robert Recorde: Tudor Scholar and Mathematician by Gordon Roberts.

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18 June – Robert Recorde, his urinal and the equals sign