The Beam

Now we are on the top floor and this is the beam, only half of the beam is seen here as the other half is outside where it would be connected to a pump rod (made of large section timber) and this would go down to the depths of the mines, 700 fathoms would not be unusual. The beam (known as "the Bob" in Cornwall) pivots on the end wall of the engine house and rises and falls up to about 12 feet (the stroke of the engine). This beam sometimes weighs up to 50 tons see-sawing on the bob-wall creates much stress on the structure of the building and the bob-wall is often 8 feet thick granite.

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