Plate, brass tube and iron frame on vacuum apparatus by unknown artist Diagram of a vacuum apparatus constructed from a brass tube with an iron frame, screwed to mahogany beams. Annoted to indicate where it should be printed in the published paper. Subject: Physics Published in Philosophical Transactions as 'On the correction of a pendulum for the reduction to a vacuum: together with remarks on some anomalies observed in pendulum experiments'. Read 31 May 1832. [1832]