<p>A sensing device for use with a pressure gauge for measuring pressure in a mud carrying oil well pipe or the like includes a hollow cylindrical casing one end of which is mounted in the pipe and the other end of which is connected to the gauge. A piston slidably mounted in the casing divides the interior of the casing into lower and upper chambers, the pressure of mud in the lower chamber being transmitted by the piston and hydraulic fluid in the upper chamber to the gauge, whereby the gauge registers the pressure of the mud without direct contact therewith.</p>
