There is a curious paradox in our knowledge of the 18th Century Italian barometer maker, Christopher Bettally. On the one hand, he is reasonably well documented in the records of the time; we know he had shops in Paris and London (Oxford Street and Pimlico); his trade cards in the British Museum declaim that he was a “Constructor of Barometers, Thermometers, Hygrometers and all sorts of Phisical Instruments of Glass” and was the “Real & Sole Inventor of Philosophical Fire & Chemical Flambeaux for Lighting a Candle without Flint, Steel or Tinder.”

Bettally is well known for supplying (in 1787) a spectacular meteorology set to Lord Bute, comprising a matching pair of wheel instruments – barometer and thermometer. It is probably no coincidence that his Pimlico shop was a stone’s throw from Buckingham House, the precursor to Buckingham Palace.

And yet, despite these known facts, very few examples survive of his craft survive. Besides the Bute instruments, there are no specimens of his work recorded in the literature and, to my knowledge, no Bettally instrument has appeared on the market in recent years.

It was, therefore, very exciting to find an imposing Bettally wheel barometer, good original condition, lurking in a recent Country House sale. It is of plain design, in complete contrast to the vast majority of ‘banjos’, and is dominated by a square-section column forming the upper half, topped by a massive brass finial. The 14” dial is, again, plain, with conventional scale markings, and is elegantly signed “C.Bettally, London”.

The quality of the cabinet making in the mahogany case is awesome and all the edges are finished with barbers-pole stringing.

‘Rare’ is a much-abused term, but justified in this case.