Micro manometer:

A typical micro-manometer tube arrangement as shown in fig has a reservoir which can be moved up and down by means of micrometer screw. A flexible tube is connected between point A and the reservoir. Another flexible tube connecting point B and the other end of the reservoir is placed on an inclined surface. A reference mark 'R' is provided on the inclined portion of the tube. Before application of the pressure, the level of the reservoir is moved so as to coincide this level with the reference mark. When a pressure difference is applied, the liquid levels will be disturbed. The micrometer arrangement is then adjusted to vary the reservoir level so as to coincide with the reference. The extent of movement of the micrometer screw gives the pressure difference between the two points A and B.