| The Cartwheel Twopence was the largest, and heaviest, of the coins minted in Great Britain. Issued only in the year 1797, this copper coin measures 41.01mm, or 1-9/16 inches, in diameter and 5mm, or 5/16 inches thick. The cartwheel twopence coin weighs 56.51 grams, or two ounces. The coin was minted only at the Soho Mint in Birmingham, England.
The obverse of the coin bears the image of King George III in profile. Incused (i.e. stamped, hammered, or impressed) on a raised rim around the image is the legend: GEORGIUS III . D : G . REX, meaning "George III Dei Gratia (by the grace of God) King". The reverse of the coin features an image of 'Britannia' seated on an island in the ocean (with a passing ship) and holding a trident in her left hand and an olive branch in her right. The legend incused in a raised rim around the image bears the word: BRITANNIA and the date of 1797.
The cartwheel twopence was noted for two things: having been (along with the pence) one of the first coins produced by the steam powered coin press invented by Matthew Boulton ~ and ~ by weighing exactly two ounces, could be used as a weight for measuring other products. The smaller "cartwheel" pence or penny, which weighed exactly one ounce, was also used by merchants in the process of weighing.