Abstract: The element is constituted by an elongated tube whose height is equal to or exceeds 0.8 times its diameter, and which has a bearing surface on one face of the members to be assembled and a bearing surface on one face of a nut, the two bearing surfaces being interrupted by a slot completely passing through the tube in a generally longitudinal directional section, a displacement being provided on each of the bearing surfaces and between the zones of the bearing surfaces respectively located on either side of the slot, the two displacements being in opposite directions in the longitudinal direction of the element.

Abstract: Automatic high insulation switch with low consumption level and small overall dimensions. The switch is associated with an apparatus for measuring very low currents (10.sup.-7 to 10.sup.-14 amperes) comprising an amplifier controlled by an input field effect transistor. The invention aims to switch on the amplifier's very high value resistors with the aid of magnetically controlled, flexible reed interrupters or switches, actuated by a permanent magnet, which is itself controlled by a conventional servomechanism having a motor and a potentiometer controlled by a microprocessor. Other interrupters ensure the protection of the transistor. The invention is more particularly used for measuring currents supplied by ionization chambers.