As well as improving the flush mechanism, Cummings included an S-trap (or bend) to retain water permanently within the waste pipe, thus preventing sewer gases from entering buildings.

The Earl of Bute and his family commissioned a series of elaborate barrel organs with which Cumming was involved.

[7][8] By 1763 he had premises in Bond Street, London, and "had acquired a sufficient reputation to be appointed a member of the commission set up in that year to adjudicate on John Harrison's ‘timekeeper for discovering the longitude at sea’".

[10] He wrote books about watch and clock work, about the effect on roads of carriage wheels with rims of various shapes, and on the influence of gravity.

In 1766 he made a similar model for his personal use, which on his death was purchased by Luke Howard who used it for his observations within the book The Climate of London.

[5] In 1770 he is credited with the invention of the microtome, a machine for making extremely thin slices as used in slide-preparation, in conjunction with John Hill.

[12] He also linked the water inlet valve to the flush mechanism to allow the pan to be emptied and refilled by pulling a single handle.