The Great Pump Room is a spacious saloon, ornamented with
Corinthian pillars, and a music-gallery, and a Tompion clock,
and a statue of Nash, and a golden inscription, to which all the
water-drinkers should attend, for it appeals to them in the cause
of a deserving charity.

Mr. Tompion was a founding member of England’s famed Clockmaker’s Guild of the 1630s

And a tompion is:
Tompion
(n.) A stopper of a cannon or a musket. See Tampion.
(n.) A plug in a flute or an organ pipe, to modulate the tone.
(n.) The iron bottom to which grapeshot are fixed.