PURPOSE: To prevent the yield of residual strain, by combining many long flexible strip shaped steel plates having a thin width on the outside of a flexible tube of a measuring pipe.
CONSTITUTION: A probe comprises a steel pipe 1 and a rubber tube that covers the pipe 1 and encloses a self-boring mechanism. In order to prevent the breakdown of the rubber tube 2, a metallic cylindrical pipe 3 with slits is applied on the tube 2. Long, narrow, strip shaped flexible plates are formed by a steel for thin springs. Many steel plates are combined by using upper and lower end rings 6 and 6', and a protecting device for the cylindrical rubber tube 2 is provided.