MEASURING GAUGES, APPARATUS, INSTRUMENTS, AND ACCESSORIES FOR MEASURING AND TESTING DIMENSIONS, ANGLES, AND SHAPES-NAMELY, CALIPER GAUGES, SLIP GAUGES, SLIP GAUGE ACCESSORIES FOR ASSOCIATING A PLURALITY OF SLIP GAUGES IN VARIOUS ASSEMBLAGES FOR VARIOUS MEASURING PURPOSES, THE SAME BEING HOLDERS, JAWS, STRAIGHT EDGES, SCRIBERS, CENTRE POINTS, AND MOUNTING BASES; PLAIN, AND THREADED TAPER GAUGES; MEASURING RODS OR BARS; TAPER, AND HARDENED AND GROUND, PARALLELS; VERNIER GAUGES; SQUARES; SINE BARS; PLANAR, AND SHAPER, GAUGES; MICROMETER GAUGES; SPLINE, AND SERRATION PLUG GAUGES; SPLINE AND SERRATION RING GAUGES; MASTER GAUGES FOR TESTING PLUG AND RING SPLINE AND SERRATION GAUGES; CONCENTRICITY AND RECEIVER GAUGES; OPTICAL PLANE GAUGES, ALSO KNOWN AS OPTICAL FLATS, FOR GAUGING THE FLATNESS OR PLANE OF MACHINED SURFACES; INTERNAL TAPER GAUGES; INTERNAL TAPER THREAD GAUGES; PRECISION DIMENSION MEASUREMENT MACHINES; TAP FLUTE COMPARATORS; LEVEL COMPARATORS; INTERFEROMETERS FOR CHECKING THE PLANE OR FLATNESS AND PARALLELISM OF LAPPED SURFACES ON SLIP GAUGES AND OPTICAL SURFACE PLANE GAUGES OR OPTICAL FLATS; FLANK ANGLE TESTING MACHINES; HOB AND WORK CHECKING MACHINES; CAM MEASURING MACHINES; DRILL POINT GAUGES FOR MEASURING THE ANGLE OF A DRILL POINT; THREAD MEASURING CYLINDERS AND PRISMS; SURFACE PLANE GAUGES FOR TESTING THE FLATNESS OF WORK-PIECE SURFACES; AND FATIGUE AND STRESS TESTING MACHINES