A quack; so called from one Rock, who was the “Holloway” of Queen Anne's reign.
Oh, when his nerves had once received a shock, Sir Isaac Newton might have gone to Rock.
The Ladies' Rock. A crag in Scotland under the castle rock of Stirling, where ladies used to witness tournaments.
“In the castle hill is a hollow called The Valley about a
square acre in extent, used for justings and tournaments. On the south
side of the valley is a small rocky pyramidical mount, called The
Ladies' Hill or Rock, where the ladies sat to witness the
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894