Abstract: There is described a meter for the flow rate or the speed of a gas stream, by converting an electric potential metering, which comprises a pair of so-called outer tubular electrodes connected to an electric voltage source and through which the gas stream will pass, said electrode pair forming with a common electrode two series-connected electric fields, as well as an ion source which is located inside the one electrode while the common electrode is connected to a measuring circuit responsive to the potential of said electrode, in which both outer electrodes are arranged on either side and with a spacing relative to the common electrode which is also a tube-like shape.

Abstract: Axially aligned conductive metal cylindrical members on opposite sides of a printed circuit plate define a first measuring chamber and a second reference chamber on opposite sides thereof. The bottom of one cylindrical member forms the first electrode of the reference chamber and a plate closing off the end of the measuring chamber remote from the printed circuit plate forms the first electrode of the measuring chamber.

Abstract: The invention has for its object a device for measuring the slope parameters of a material contained in a cylinder rotated around the axis thereof.This device, which senses radiations generated by radio-isotopes passing through the cylinder and the material contained therein, comprises means 1 generating the said radiations and means 8a, 8b picking up the latter fitted outside the cylinder in such a manner that, during the rotation thereof, the radiation generated by the radio-isotopes passing through the slope of material 5 in at least two separate locations is sensed in a specific point of the cylinder, as well as means for analyzing the signals received by the means sensing said radiation.This device is to be used together with a rotating furnace and particularly a cement kiln.