The Latin legends translate as on the obverse "William and Mary by the Grace of God," and abbreviated on the reverse as "King and Queen of Great Britain, France and Ireland." Additionally on the edge as "An ornament and a safeguard, in the third year of the reign."
We note the silver output for the calendar year of 1691 was a mere £3,731 and would have been spread across Crowns, Halfcrowns and Small silver, the second lowest of the reign.