Adhesion discs, 1752.
© Science Museum / Science & Society Picture Library
Both these pieces of marble have a flat surface. These surfaces adhered when placed together because of the presure of the atmosphere, but fell apart in the near vacuum produced by an air pump. This apparatus is asociated with Dr Stephen Demainbray (1710-1782), a science lecturer of the 18th century. This experiment was unreliable and Demainbray left it out of later syllabuses of his courses of lectures.