Built and patented by the French engineer Eugène Bourdon (1808-1884) who had invented it in 1849, this is a metal manometer inside a sturdy painted iron case having an elliptical cross section (23 x 32.5 cm, depth 6 cm) that has at the top a dial with a scale for reading the pressures and lower down a brass button bearing the inventor's initials E.B. An L-shaped wooden support, to which it is attached, keeps it in a vertical position.
It is composed of a copper tube having an elliptical cross section. It has thin walls and is flexible, slightly flattened on one side and bent twice into a spiral in the flattened part.
One of the ends is attached laterally to the case with a pipe union with a cock which allows connection to the recipient in which the pressure is to be measured; the other end is free and closed and terminates with a steel index that moves on a graduated scale.