Abstract: A plumb weight hung onto a plumb wire anchored firmly at one end bears a laser light emitter which lies opposite a stationary photoelectric receiver. The receiver has a photodetector arrangement which is connected downstream of an optical system and a matt screen. The light emitter and receiver form an optical position measuring system. Relative movements between the anchoring point of the plumb wire and hence between the plumb body and the receiver transverse to the vertical direction result in a change of the position of the point of incidence of the light beam on the photodetector arrangement. By measuring the respective position of this light spot, the degree of movement of the plumb body and hence of the plumb wire anchoring point relative to the receiver can be determined.

Abstract: The tubing system comprises a number of measuring stops or surfaces arranged in a predetermined mutual spaced relationship. The spacing is utilized for determining the displacements in the material enclosing the tubing. This displacement is ascertained by a measuring probe introduced into the tubing from the outside. The measuring stops are provided on measuring tube unions or coupling sleeves in order to ensure that displacements in the material can also be transmitted to the measuring stops even in relatively soft material without a stiffening effect of the tubing. The connection between the measuring tube unions or coupling sleeves takes place exclusively through a telescope-type protecting tube insert. A rigid anchoring of the measuring tube unions or coupling sleeves to the inner wall of an accommodating hole or bore hole provided in the material to be investigated takes place through filling collars fastened to the outside of the measuring tube unions or coupling sleeves.

Abstract: A measuring tube is inserted into a bore hole for measuring underground fluid pressure and is sealed against the bore hole wall for limiting the areas or regions in which the pressure measurement is to occur. A measuring cell is inserted into the measuring tube wall in each of these areas or regions and includes a mobile pressure sensing element against which acts the pressure of the medium surrounding the measuring tube. An end of the pressure sensing element projects into the inner space of the measuring tube and, for measurement, a measuring wheel of a measuring probe is brought into position underneath the end of the pressure sensing element such that the latter is moved radially outwards against the pressure exerted on it. The force which thus acts on the measuring wheel is determined by a measuring device for measuring the pressure. The medium to be measured does not enter or leak into the measuring tube since the measuring cell is sealingly inserted into the measuring tube.

Abstract: In the medium to be examined there is embedded a measuring tube which possesses at its inner surface essentially equidistantly spaced measuring markers. These measuring markers are in the form of mechanical stops or impact members having an impact surface forming part of a right circular cone. To determine the spacing between neighboring measuring markers there is provided a measuring probe or sensor having two measuring heads connected with one another, by means of a connection tube, such that they are relatively shiftable in the lengthwise axis of the measuring probe. Each measuring head is constructed as a mechanical counter stop having an impact or stop surface forming part of a spherical surface. Internally of the connection tube there is arranged an inductive length transmitter producing an output signal characteristic of the spacing between the measuring heads.