Guys cerebrospinal manometer, 1860-1950.

UNITED KINGDOM - NOVEMBER 21: This equipment is used to measure the cerebrospinal fluid, which surrounds and nourishes both the brain and the spinal cord. Disturbances in its volume, pressure, or constituents can affect the brain, and show in behavioural changes. The needle of the instrument goes through the skin and muscles of the back, into the fluid around the spinal cord. The height of the fluid in the bore indicates the pressure of the cerebrospinal fluid. (Photo by SSPL/Getty Images)