Struck at the Royal Mint, Tower of London in 1731, this pewter medal (51 mm) is by John Crocker, the Mint’s engraver during Newton’s tenure as Master. The obverse portrait is based on the Earl of Portsmouth’s bust (the so called Conduitt bust by Michael Rysbrack); the inscription reads, “Isaacus Newtonus I.C. The figure on the medal’s reverse, copied from the pedestal of the same bust, is that of Urania, who holds a plan of the Newtonian solar system. The reverse reads, “Felix Cognoscere Causas 1726.” The Conduitt bust can only be dated from its appearance in a picture by Hogarth painted in about 1730, and is assumed to have been commissioned about the same time that Conduitt was commissioning William Kent to design the Newton Monument in Westminster Abbey, which was carved by Rysbrack. Strikes of the medal were also completed in silver and bronze, as in the Babson collection. The date 1726 on the reverse is the year of Newton s death, in the old-style calendar.