It has been suggested that this example was made by Benjamin Cole, a maker of high quality instruments in Fleet Street and who flourished between 1750 and 1766. He did not always fully sign his instruments but other similar examples are known by him. By the third quarter of the eighteenth century, the popular diagonal scale was being replaced by the more accurate vernier scale which, used in conjunction with precise scales from makers such as Ramsden, set the essential pattern of the instrument for the next one hundred and fifty years.