St Mary's Turret Clock

The clock movement

The clock by William Potts and Sons of Leeds was installed in 1901 at the same time as the ring of five bells and as part of the same bequest. It sits in the bell-ringing chamber of the tower — directly above the chancel. It tells the time on two dials, one on the east face of the tower, and one on the north.

The clock movement is of flatbed construction, that is to say the main frame is constructed of a solid cast iron casting with the wheel bearings bolted to it, unlike earlier turret clocks where the frame containing the wheels was fabricated from several posts and strips of cast iron, and before that, wrought iron. This flatbed frame measures 4 ft 10 in wide by 1 ft 8½  inches deep, with ‘W Potts & Sons’ cast into the front rail.

The going train (time-keeping section) is in the middle; the hour-striking section is at the left, and the chiming train at the right. The clock strikes the hours on the tenor bell (lowest in pitch) hung in the bell chamber above, and chimes the quarters on the other bells. The chiming levers and wire rods can be seen protruding at the right of the movement with the weighted lever lying across them that can be hitched down to ‘pull off’ the bells when not required to chime.

The wire leading upwards at the left strikes the tenor bell hammer, and the rods connected with a universal joint are the ‘leading-off’ work that moves the hands.

Modifications

A later faceplate on the frame tells us that the movement of the clock was reconditioned in 1961 by Wm Potts & Sons. In fact it was altered drastically. The mechanical escapement was replaced by an electrically operated time-controller, and the pendulum and a number of train wheels were removed. All the weight-driven winding work – barrels, pulleys and weights – were replaced with two ¼ horsepower motors to drive the hour striking and chiming respectively. The 1961 time-controller was itself renewed some time after 1978.

Today, when hand-winding is to be given up as impractical, the philosophy is to install automatic winding with the minimum of mechanical intervention, to record every change in the procedure, and to retain any part removed. The process is to be entirely reversible.

This was not the case in 1961, however. As the missing parts seem not to have been kept or even recorded, it is hard to ascertain what sort of escapement the clock originally possessed. Clocks by Wm Potts & Sons were made with a variety of escapements such as gravity, dead-beat and pin-wheel.

But in 1901, Potts were still regularly using the gravity escapement, and a specimen made just a few months before the clock at Goathland still exists – and in fine working condition –  about four miles away at the church of St Hilda, Egton.

It is therefore very likely that the Goathland clock was constructed to the same pattern as Egton’s, with the addition of a chiming train. As evidence pointing towards that, we are fortunate to possess a handwritten letter which describes the new Egton clock in some detail and mentions a clock being currently constructed at Goathland. The letter, in fine copperplate writing and believed to have been written by someone at Wm Potts & Sons, is now at the County Records Office. We have extracted the details given below.

A letter about the Egton church clock

“The Escapement is the double 3-legged gravity by Lord Grimthorpe – the most perfect ever introduced for correct timekeeping in large clocks – with a 1¼ Seconds Compensated Pendulum attached composed of zinc & iron tubes with a steel rod through the centre, and a cylindrical shaped bob of solid cast iron, with a regulating cup for finer adjustment by small weights. The Pendulum, being Compensated, will not be affected by any variations of temperatures.         

“The large or Main Wheel of the Going Part is 12 inches in dia^r of gun metal cut and polished on the Engine from the solid also the smaller wheels & the Pinions of the best cast steel hardened & tempered. The Hour Striking Main Wheel 14 inches in diameter with cams attached or fixed on it for lifting a hammer of the proper size for bringing out the full tone of the bell, with wrought iron stem or shank & pivotted into a strong iron frame with a hardened & tempered steel check spring attached. The barrels are of iron with 2 hardened & tempered steel clicks and springs attached. The fly is placed behind the clock frame with a gun metal ratchet squared on the arbor & 2 hardened & tempered steel clicks and springs attached. The cords are of the best steel wire running over iron block pulleys bushed with gun metal & pivotted in. The weights are of iron, cast in slips for easier adjustment.

“There are also cranks, levers, connections, stands, apparatus for pulling off the hammer during the time the bells are rung for service, and everything requisite and necessary in a First Rate Clock.

“The work having been carried out by Mess^rs W^m Potts & Sons of Leeds, Newcastle-on-Tyne makers of the Lincoln Cathedral, Whitby, Pickering, Scalby, Loftus, ... etc ... & other Church Clocks, & now erecting new Church Clocks at Goathland, Etherley, Ulverston, Ambleside, Cranoe, Leicestershire, & large Clock & Chimes for a Church in Lincolnshire. Etc.”

The firm of Wm Potts & Sons, of Guildford Clock Works, Leeds, has since been amalgamated, together with Joyce of Whitchurch, into the firm of Smiths of Derby, a firm still servicing the clock and operating successfully today.

The same escapement as Big Ben?

The double three-legged gravity escapement was invented by the barrister and clock expert, Lord Grimthorpe (Edmund Beckett Denison) specifically for the Palace of Westminster clock, and like the ‘Westminster Chimes’, was immediately taken up for other clocks around the country. For several decades it was the escapement of choice for turret clocks where the hands are very exposed and subject to adverse weather conditions such as rain, snow and high winds, as well as perching birds.

The escapement brilliantly resolves two apparently conflicting aims:

1.    to use as much power as necessary to overcome variable external forces acting on the hands, and variable frictional forces in the gearing leading to the hands (the leading-off and motion work), especially where universal joints are used to change the shaft direction.

2.    to apply a small, constant force to the pendulum to keep it swinging in a uniform arc (ie uniform timekeeping), through an escapement that allows the pendulum to ‘unlock’ the train by a small increment at the two extremities of its swing without the variations mentioned in (1) affecting the pendulum’s arc.

Without the missing components we can not say for certain what escapement the Goathland clock had, although the gravity escapement is most likely and has a parallel in the next parish.

It is almost certain that the pendulum was 4 foot in length like Egton’s, that is, it beat 1¼ seconds. The movement is mounted above the floor on massive cast iron brackets, and its height above the floor – appropriate to a 4 ft pendulum – requires a wooden platform in front for access at chest height.