Abstract: A rock anchor assembly comprising a tensioning element adapted to be inserted into a bore hole and to be clamped therein, the outer end of which projecting from said bore hole being adapted to be tensioned against a rock wall by means of an anchor plate, the inner end of said tensioning element inserted into the bore hole being provided with a spreading jacket clinging into said bore hole and being adapted for tensioning with the inner end of the tensioning element by means of a spreading wedge upon turning a clamp nut, and wherein said clamp nut is screwed on a threaded tensioning jacket being adapted for tensioning with the outer end of said tensioning element with the aid of tensioning wedge means upon turning the clamp nut. A method of installing said rock anchor in a wall is also provided.

Abstract: A carpet stretcher device comprising a body case having a handle fixed to the upper surface thereof, an electromagnetic coil axially installed in the body case, a plunger axially slidably fitted in the inner surface of the electromagnetic coil and normally urge rearwardly by a spring, and a spindle fixed to the rear end of an engaging head for engagement with carpets and axially slidably fitted in the front end of the body case, the arrangement being such that upon energization of the electromagnetic coil the plunger is advanced to strike the rear end of the engaging head with its front end.

Abstract: A device comprising a set of fine, uniform, translucent fibers mounted on a suitable holder. When used in conjunction with appropriate neutral density optical filters, if necessary, on suitable particle sizing instruments, the device can easily and quickly be used to perform three important functions--namely, to accurately check the instrument calibration or response to particle size, to locate the limits of the optical depth of field in the particle illuminating beam, and to test the ability of the instrument to detect and register all validly sampled, single particle events.

Abstract: Polyisocyanurate foam is produced by reacting a polyisocyanate component with an anhydrous reaction product between a dibasic acid anhydride and a partially alcoholated polyether-polyol with an alkali metal hydroxide and/or alkaline earth metal hydroxide. The reaction product acts as a catalyst for trimerizing the polyisocyanate and also as a polyether-polyol component.

Abstract: An electrical laminate comprising layers of a polyester resin-impregnated fibrous cellulosic substrate is disclosed. The substrate is preimpregnated with a nitrogen-containing composition having (a) an N-methylol or N-lower alkoxymethyl group attached to said nitrogen atom, and (b) an unsaturated group capable of copolymerizing with a cross-linking monomer present in the polyester resin.

Abstract: A heat exchanger unit (20) is provided to be placed upon a fireplace floor (17) and attached to a heatalator or heat form (57) to enhance the heating efficiency of a conventional fireplace. The unit receives room air through apertures (33) in its front wall (21) and conducts the cool air through a plurality of upwardly angled tubes (40) toward the rear wall (25) of the unit as the air is continuously heated by the surrounding kindling wood (18), charcoal and ashes. Mounting holes (41) are provided on the rear wall of the unit in order to attach the heat exchanger to the rear wall (13) of the fireplace. Grate holes (30) are positioned along the bottom wall and are capable of being aligned with a plurality of shaker holes (52) formed in at least one shaker grate (51) slidable over the bottom wall which is positioned in at least one elongated aperture (37) formed in the front wall.