21

Grave [21] is the small mid-18th century headstone of Henry Matthews which has an hourglass running out of time.

A winged-hourglass was a common feature of gravestones in the 18th century. In fact, it was not uncommon for the dead to be buried with an actual hourglass to represent the sands of time having run out. In masonic symbolism it is often paired with the scythe, another emblem of how easy it is to sever the boundary between life and death.