A fine and rare late 18th century pocket chronometer movement of the 'best kind'
This movement is illustrated and discussed in Mercer, John Arnold & Son, AHS, London,1972 Plate 105. It has been suggested that this movement may have originally been supplied with the larger double S balance and a cut out in the edge of the backplate above one of the pillars does lend some support to this theory. However, the cut out section has never been drilled to accept the pin that would fix the pillar and thereby allow the balance free movement.
In 1791, Arnold charged 120 guineas for a pocket chronometer of the best kind in a gold case. One of the second kind in a gold case would cost less than half this figure, between 41 and 55 guineas, depending on the number of jewelled bearings.