| These instructions describe a sea clock inspired by John Harrison, who won the Board of Longitude Prize established by the British Government in the 18th century for a clock which could accurately tell the time at sea and hence establish a ship's longitude at any moment. A pendulum is useless on a boat, and as a result, John Harrison invented the unique twin balance arms and grasshopper escapement.
Whereas latitude at sea had always been established by simple observation of the sun and other heavenly bodies, the method of arriving at one's destination had been to sail until the latitude of the destination had been reached, then to run along its parallel. Computing longitude by dead reckoning necessarily involved considerable and growing uncertainty of a ships position.
John Harrison spent six years from 1729 until 1735 in building his first marine timekeeper. The Meccano replica of this clock embodies two of its most important features - the linked balance arms, which give the clock a visually fascinating restful and attractive quality, and the unique frictionless 'grasshopper' escapement with the subtle lock and release action of the pallets.
Although not an exact replica of Harrison's Clock, it does follow quite closely the design of Sinclair Harding, a leading firm of clockmakers.
Instructions include the Clock Plates, Balance Shaft Roller Bearings, Going Train, Motion Work, Planetary Weight, Bull motor, Balance Arms and Pallets, Control Spring, Cross linking, Escape Wheel and Jig, Motor Fitting, Adjustment, Oscillation, Action of Grasshopper Spring, Faces, Timing, Clock Case, Glazing, and Plinth.
A 20 page instruction leaflet is illustrated with eighteen colour photographs, an additioanl 16 page supplement contains fourteen line drawings and parts list, and there are two clock face drawings on gloss paper to cut out.
Please note these Model Plans are designed by individual Meccano modellers and may use parts not currently available. The level of instruction detail is dependent on the original modeller and varies from plan to plan. These are instructions only.