ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY
Whetstone of Witte. This work is by the Welsh mathematician and physician Robert Recorde (1512-1558). It covers whole numbers, the extraction of roots and irrational numbers. It contains the first recorded use of the equals sign and the first use of the plus and minus signs in an English language book. This is the title page of the first edition, published in 1557 in London.
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