Born around 1510, Robert Recorde was the second and last son of Thomas and Rose Recorde[3] ofTenby,Pembrokeshire, inWales.[4]
Recorde entered theUniversity of Oxford about 1525, and was elected a Fellow ofAll Souls College there in 1531. Having adopted medicine as a profession, he went to theUniversity of Cambridge to take the degree of M.D. in 1545. He afterwards returned to Oxford, where he publicly taught mathematics, as he had done prior to going to Cambridge. He invented the "equals" sign, which consists of two horizontal parallel lines, stating that no two things can be more equal. It appears that he afterwards went to London, and acted as physician to KingEdward VI and toQueen Mary, to whom some of his books are dedicated. He was also controller of theRoyal Mint and served as Comptroller of Mines and Monies in Ireland.[5] After being sued for defamation by a political enemy, he was arrested for debt and died in theKing's Bench Prison,Southwark, by the middle of June 1558.
The first known equation, equivalent to14x + 15 = 71 in modern notation, fromThe Whetstone of Witte. (The solution isx = 4)Recorde's introduction of theequals sign inThe Whetstone of Witte, "to avoid tedious repetition".
Recorde published several works upon mathematical and medical subjects, chiefly in the form of dialogue between master and scholar, such as the following:
The Grounde of Artes, teachings the Worke and Practise, of Arithmeticke, both in whole numbers and fractions (1543),[4] the first English language book onalgebra.
The Pathway to Knowledge, containing the First Principles of Geometry ... bothe for the use of Instrumentes Geometricall and Astronomicall, and also for Projection of Plattes (London, 1551)
The Castle of Knowledge, containing the Explication of the Sphere both Celestiall and Materiall, etc. (London, 1556) A book explainingPtolemaic astronomy while mentioning theCopernican heliocentric model in passing.
The Whetstone of Witte, whiche is the seconde parte of Arithmeteke: containing thextraction of rootes; the cossike practise, with the rule of equation; and the workes of Surde Nombers (London, 1557). This was the book in which theequals sign was introduced within a printed edition.[6] With the publication of this book Recorde is credited with introducing algebra into the Island of Britain with a systematic notation.[7][8]
A medical work,The Urinal of Physick (1548), frequently reprinted.[9]
Most of those works were written in the form of acatechism.[6]Several books whose authors are unknown have been attributed to him:Cosmographiae isagoge,De Arte faciendi Horologium andDe Usu Globorum et de Statu temporum.[10]
^Robert Recorde,The Whetstone of Witte (London, England: John Kyngstone, 1557),p. 236 (although the pages of this book are not numbered). From the chapter titled "The rule of equation, commonly called Algebers Rule" (p. 236): "Howbeit, for easie alteration ofequations. I will propounde a fewe examples, bicause the extraction of their rootes, maie the more aptly bee wroughte. And to avoide the tediouse repetition of these woordes: is equalle to: I will sette as I doe often in worke use, a paire of paralleles, or Gemowe [twin, fromgemew, from the Frenchgemeau (twin / twins), from the Latingemellus (little twin)] lines of one lengthe, thus: = , bicause noe .2. thynges, can be moare equalle." (However, for easy manipulation ofequations, I will present a few examples in order that the extraction of roots may be more readily done. And to avoid the tedious repetition of these words "is equal to", I will substitute, as I often do when working, a pair of parallels or twin lines of the same length, thus: = , because no two things can be more equal.)
^John Hall, "An Historiall Expostulation", p. 60. InEarly English Poetry, Ballads, and Popular Literature of the Middle Ages, v. XI. London: T. Richards, 1844
Gareth Roberts and Fenny Smith, editors (2012).Robert Recorde: The Life and Times of a Tudor Mathematician (University of Wales Press, distributed by University of Chicago Press) 232 pages
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This article incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Recorde, Robert".Encyclopædia Britannica. Vol. 22 (11th ed.). Cambridge University Press. p. 966.
