Abstract: The invention is an apparatus for measuring pressure, which comprises a pressure communicating device (3) for location at a point (4) at which pressure is to be measured, a primary tube (1) containing a fluid for linking the pressure communicating device (3) to a control point (9) where the pressure information is required, a sealing device for sealing the primary tube (1) so as to form a closed system when the pressure communicating device (3) is closed, a pressure control device (6) for changing the pressure of the fluid within the primary tube (1), a volume measuring device (8) for measuring changes in the volume of the fluid within the primary tube (1) as the pressure of the fluid is varied, a pressure measuring device (7) for measuring the pressure of the fluid at some point within the fluid, and device remote from the control point (9), and a transmitter device for transmitting pressure information from the pressure measuring device to the control point (9).