Pair of marble adhesion discs, with band and ring handle.
Pair of marble adhesion discs, before 1753. Both these pieces of marble have a flat surface. These surfaces adhered when placed together because of the pressure of the atmosphere, but fell apart in the near vacuum produced by an air pump. This apparatus is associated with Dr. Stephen Demainbray (1710-1782), a lecturer on experimental philosophy. This experiment was unreliable and Demainbray left it out of later syllabuses of his courses of lectures.