Drawing, 'Ting Tang engine Bob', paper / ink, Richard Michell for Boulton and Watt, Cornwall, England, 1780.
An ink drawing showing a plan of the beam, or bob, for the Ting Tang engine, which began to be erected in May 1778. The drawing shows the beam, with six rods hanging via chains from arch-heads (cams in the form of circular arcs), and the upper half of the cylinder. Text handwritten in ink can be seen in the top right corner. Additional notations and measurements are also handwritten in ink on the drawing. On the reverse side of the page is a draft drawing of the beam.
Handwritten in ink in top right corner 'Ting Tang Engine Bob / This / Engine was Began to Put together / on the first of May 1778. / And was the first engine Mr Watt / Erected in the County of Cornwall.'