Grasshopper escapement longcase clock in ebonised pine case by James Harrison, brother of John Harrison, Barrow-upon Humber, North Lincolnshire
The 11 inch wooden dial is hand-painted with a silvered hour circle. Indications for seconds and day-of-month show through apertures.
Within the door of the case is a window displaying an equation-of-time table in John Harrison’s hand. It is corrected for the change to the Gregorian Calendar in 1752. 8-day movement, plates and wheels of oak, roller pinions of lignum vitae and brass. Temperature compensated gridiron pendulum. Adjustable cycloid cheeks. Maintaining power. Signed in the arch of the dial 'Barrow, James Harrison' and 'James Harrison 3rd 1728 Barrow' on calendar wheel.
One of two regulators kept in John Harrison’s cottage and set by the stars, using his doorpost and his neighbour’s chimney for observation.
Clockmakers' Museum No. 553