Abstract: A parallel straightedge which may be attached to any drawing table wherein the straightedge is arranged for adjustment and is provided with a braking arrangement to allow the straightedge to be fixedly held in any given position and/or orientation. The bottom of the straightedge is arranged on a pair of rollers outboard the working area in order not to smudge the drawing contained thereon. A removable plastic insert along the edge of the metal straightedge bar provides a consistent transparent ruling edge for drawing straight lines while providing a nick-free edge as a guide for cutting instruments when the transparent edge is removed.

Abstract: A completely submersible pressure-sensing transducer contains an air vent tube for providing a pressure differential relationship between the hydrostatic head and the atmosphere. The transducer contains associated electronic circuitry for providing direct read-out and absolute units.

Abstract: An attachment for a drafting board comprising an elongate cylindrical chamber adapted to be removably attached to an edge of a drafting board, such cylindrical chamber containing a longitudinal opening through which paper may be withdrawn or retracted, a rotor mounted within the chamber for receiving a roll of drafting paper, spring means mounted within the chamber for yieldably pressing the paper against the surface of the rotor, said spring means being adapted to be withdrawn to enable placing the paper within the chamber and a crank for rotating the rotor.