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Mathematical Treasure: Blagrave's Mathematical Jewel

Frank J. Swetz (The Pennsylvania State University)

John Blagrave (ca.1561-1611) was a Tudor mathematician and instrument maker. He was a strong advocate of the applications of mathematics and claimed that mathematics provided “general advantage and [was] indispensible in many conveniences of life.” Blagrave published several books on the construction and use of measuring instruments. The Mathematical Jewel (1585) was his most popular and influential publication. The “Jewel” of the title was an astrolabe designed by Blagrave and considered superior for its time. The title page (shown above) proclaims the book’s contents:

The mathematical ievvel, shewing the making, and most excellent vse of a singuler instrument so called: in that it performeth with wonderfull dexteritie, whatsoeuer is to be done, either by quadrant, ship, circle, cylinder, ring, dyall, horoscope, astrolabe, sphere, globe, or any such like heretofore deuised: ... The vse of which iewel, is so aboundant and ample, that it leadeth any man practising thereon, the direct pathway ... through the whole artes of astronomy, cosmography, ... and briefely of whatsoeuer concerneth the globe or sphere: ... The most part newly founde out by the author, compiled and published ... by Iohn Blagraue of Reading gentleman and well willer to the mathematickes, who hath cut all the prints or pictures of the whole worke with his owne hands. 1585.

Used by the permission of the Folger Shakespeare Library, Washington, D.C.

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: Blagrave's Mathematical Jewel," Convergence (March 2014)