Abstract: An electrical structure having a wire conductor secured to a supporting substrate is fabricated by stitching the substrate with a sewing machine using a wire as one sewing filament of the machine. The particular electrical structure described is a parabolic antenna having a wire screen reflector consisting of a plurality of wire screen sections or "squares" secured in checkerboard fashion to a supporting frame with the edges of adjacent squares in electrical contact. Each square is fabricated by utilizing the wire stitching technique of the invention to lock stitch a supporting substrate in a grid pattern consisting of the stitched wires disposed in intersecting parallel rows and electrically joined to one another at their intersections to form a screen square.

Abstract: An optics module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The optics module embodies a frame which adjustably mounts the optical elements of the holographic system of the instrument in a manner which facilitates initial alignment of the system and preserves the alignment during instrument operation.

Abstract: An improved fluid expulsion device of the class comprising an expulsion container containing a diaphragm adapted to be displaced by a pressure fluid acting on one side of the diaphragm to expel a second fluid at the opposite side of the diaphragm. The diaphragm is bonded to the inner container wall, either by electrodeposition of a metal on the wall in such a way as to form the diaphragm on and in bonded relation to the wall or by adhesively bonding a preformed diaphragm to the wall by adhesive bands, whereby displacement of the diaphragm is accompanied by peeling of the latter from the container wall without wrinkling, tearing, or ripping.

Abstract: A drill module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The drill module embodies a drill which is normally retracted from the field of view of the holographic system to permit unobstructed holographic recording of the selected wall surface region and which is extended into the field to drill the stress relief hole in the interval between the two holographic recordings.