Tag Archives: Gemowe lines

There Ain’t ‘Alf Some Clever Bastards – Part Twenty Seven


Robert Recorde (1512 – 1558)

The equals sign (=) and the plus sign (+) are such fixtures in our system of mathematical notation that it is sometimes difficult to conceive of how we coped without them. Some clever bastard must have devised them and this is where the latest inductee into our Hall of Fame, Robert Recorde, comes in.

Our Robert was born into a respectable family in Tenby in Pembrokeshire in 1512 and entered Oxford University in 1525. He was elected a fellow of All Souls College in 1531 and decided to specialise in what passed for medicine in those days. He transferred his allegiance to Cambridge University where he studied for a M.D in 1545. Returning to Oxford he taught medicine and then moving on to London became the physician to King Edward VI – even his ministrations couldn’t halt the untimely demise of the sickly boy king whose passing heralded the reign of Bloody Mary – and also became controller of the Royal Mint and Comptroller of Mines and Monies in Ireland.

But it was as a mathematician that Robert achieved lasting fame. Prior to his development of the now customary notation for equals, mathematicians had to write out the Latin word aequalis, meaning equals, every time. This of course became very tedious if you were doing any form of extensive calculation. In his book “The Whetstone of Witt” published in 1557 Recorde acknowledged the inadequacy of the then current form of noting equality and proposed the adoption of what he called the Gemowe lines, from the Latin gemellus meaning twin,. “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 can be more equal”.

The notation he developed was wider than that which we use today but nonetheless it was a stroke (or perhaps two) of genius. Not everyone agreed with Robert though and mathematicians, who seem to have been a conservative lot, did not universally adopt the notation until the 18th century. Some preferred to use the symbol || whilst others persisted with the abbreviations ae or oe, denoting aequalis. Eventually, the notation became the norm.

But, as we have often found with our inductees, genius does not always equate with happiness. Recorde was sued for defamation by a political enemy in the turbulent times following Mary’s accession and found himself languishing in the debtors’ prison in Southwark, the King’s Bench Prison, where he subsequently died.

Robert, for introducing the Gemowe lines, you are a worthy inductee to our Hall of Fame.


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