Regulator clock with gravity escapement, English, c 1850.
© Science Museum / Science & Society Picture Library
This weight-driven clock with gravity escapement was made by J M Bloxham. In a gravity escapement the wheel train does not act directly on the pendulum, but is arranged to lift gravity arms which, when falling, give impulses to the pendulum. Such impulses are constant and independent of any variations which may occur in the power transmitted by the wheel train. The gravity escapement shown was the immediate forerunner of Lord Grimthorpe's (1816-1905) gravity escapement as employed in the Houses of Parliament clock, otherwise known as 'Big Ben'.