text: The word rheometer comes from the Greek, and means a device for measuring main flow.  In the 19th century it was commonly used for devices to measure electric current, until the word was supplanted by galvanometer and ammeter.  It was also used for the measurement of the flow of liquids, in medical practice (flow of blood) and in civil engineering (flow of water).  This latter use persisted to the second half of the 20th century in some areas.  Following the coining of the term rheology the word came to be applied to instruments for measuring the character rather than quantity of flow, and the other meanings are obsolete. (Principal Source: Oxford English Dictionary) The principle and working of rheometers is described in several texts.