Sunday 6 June 2021

Thomas Cooke and the rotation of the Earth


York Herald Saturday 3rd May 1851

The Rotation of the Earth proved in York Minster

We have the pleasure to announce that, by means of very simple apparatus, constructed and set up by our clever optician Mr T Cooke, the experiment of the Earth’s rotation has been very successfully performed in York. The arrangement was made by Mr Cooke in the north western tower of the minster, over the ‘ringing floor’, which was graduated for the purpose.

The pendulum weight was suspended by wire, 52 feet long, and was made to commence its vibrations in a north and south direction. In experiments of this kind, it is important to avoid irregularities of motion, twist of the suspending wire, and rotation of the pendulum ball. All this was accomplished , and the weight swung with perfect steadiness in its original sidereal plane, while the Earth revolving below it and leaving it behind, carried the meridian line in which the pendulum was set to swing, gradually and imperceptibly away, till at the end of one hour of mean time, ibis meridian differed from the line described by the pendulum on the floor 13 degrees.

By calculation for the latitude of York,, the deviation ought to have been a little above 12 degrees. The excess is probably due to the effects of air currents, and for very delicate results this may require glass screens tom the pendulum, but nothing could be more satisfactory than the general character of the mechanical proof afforded by this experiment, that the Earth turns round on its axis- a point once stoutly and imprudently denied by very learned and powerful persons, in the days of Galileo.

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