Abstract: A new acoustic sensing device or directional microphone having greater sensitivity and reduced noise. The directional microphone or acoustic sensor has a rigid, one micron thick, polysilicon membrane having dimensions of about 1 mm×2 mm. The membrane is supported upon its center by rigid supports having torsional and transverse stiffness. The differential microphone is useful in hearing aids, telecommunications equipment, information technology and military applications.

Abstract: The invention relates to a control rod or power transmission rod of tubular shape whose ends are provided with bearings and which is formed of continuous fibres or wires coated with resin and wound around internal elements of the bearings. To provide the rod with a high transverse strength, the fibres or wires are wound on the internal elements of the bearings at an angle greater than 180.degree., for example, 270.degree., and intersect each other where they leave these elements, so as to avoid forming a plane of weakness liable to fracture.

Abstract: A method of disposing a bar of rectangular cross-section includes firstly placing the bar on a first substantially cylindrical surface which is connected to a second cylindrical surface along a common generatrix. Two tangential planes along the generatrix form a dihedral angle, preferably 145.degree.. The first surface is then tilted to cause the bar to slide toward the common generatrix until it abuts against the apex of the dihedral angle. The tilt is increased until the bar either slides or tips onto the second surface. Thereafter, the bar, which rests on the second surface on one of its wider sides, is collected. An apparatus for carrying out the method includes at least two substantially cylindrical surfaces connected along a common generatrix. Two tangential planes along the generatrix form a dihedral angle, preferably 145.degree.. The cylindrical surfaces are formed on the edges of at least two rotatable members of cruciform shape.