T. Robinson, The Longcase Clock, Woodbridge, 1981
D. Roberts, British Longcase Clocks, Atglen, 1990
E. Bruton, The Wetherfield Collection of Clocks, London, 1981
C.F.C. Beeson, 'A Clock by John Hawting', Antiquarian Horology, Vol.IV, December 1964, pp.273-274
John Topping was a London clockmaker born in 1677 and apprenticed to William Grimes until 1698. He also signed himself 'Memory Master', although the reason is unknown. Tom Robinson (p.231) states that he was a maker of interesting clocks, including one in an ebonised case with centre seconds and having a rotating moon surrounded by a universal tidal dial. A clock by him with a dial of comparable design in a tortoiseshell lacquered case is illustrated, British Longcase Clocks (pp.76-77). A clock dial of almost identical design, signed Francis Gregg, is also illustrated (p.232, fig and also The Wetherfield Collection, p.197, fig.168), suggesting there was an association between the two makers.
Derek Roberts (p.74), writes that during the 1720s and 1730s clocks showed much innovation in their design and construction. Many of the leading clockmakers vied with one another to produce more important clocks, spurred on no doubt by their wealthy patrons who wished to be seen to have the finest available. Displaying the seconds in the arch is a rare feature and involves dramatically re-arranging the layout of the standard clock train.
There were a number of makers producing clocks with similar dial layouts, including Francis Gregg, John Ellicott, Richard Street and John Hawting (see Robinson pp.232-240, Roberts pp.74-75 and Beeson p.273 for some examples). One of the most successful and artistic of these was William Scafe; a good example of one of his clocks was sold, Christie's, London, Important Clocks and Marine Chronometers, 6 December 2006, lot 113.