To mount a scale plate securely in a correct direction by a method wherein a pressure transmission pipe is inserted through a thermosensitive cylinder to reduce the diameter of a link cylinder body and a union screw freely rotatable and freely movable radially is provided on the outer circumference of the link cylinder body.

A pressure transmission pipe 63 composing a pressure transmission path 42 is inserted through a thermosensitive cylinder 40 via a steel part 62 and connected to a Bourdon tube 41 of a temperature/pressure display section 35 through the thermosensitive cylinder 40 and a link cylinder body 38. A union screw 66 freely rotatable and freely movable radially is mounted on the outer circumference of the link cylinder body 38 now allowing a smaller diameter. When a water level thermometer this obtained is mounted on an object 39 to be measured, a male thread part 70 of a screw 71 for mounting the object to be measured is screwed down into a thread hole 69 of the object 39 to be measured. Then, a scale plate 33 of a display section 35 is turned in the correct direction to get a male thread part 65 of the union screw 66 screwed down on a female thread part 67 of the screw 71. At this point, the union screw 66 turns freely but the link cylinder body 38 connected to a case 34 does not rotate thereby keeping the direction of the scale plate 33 unchanged.