1,196,383. Bore gauges. C.J. HAMMOND, B.M. HAMMOND and D.C. HAMMOND, [trading as ROK-IT GAUGE CO.]. Jan. 28, 1969 [March 28, 1968], No. 14952/68. Heading G1M. A gauge for gauging the internal diameter of bores 44 comprises a disc 11 having diametrically opposed segments cut away, a block 16 at one side of the disc and two rods 19, 20, one end of each of which is pivotally attached to the block 16 whilst the other ends are attached to a block 25. The rods are equal length and the distance between pivot pins 23 and 24 is equal to the distance between pivot pins 29 and 30. The disc 11 is secured to the block 16 by a screw 38 and a disc 31, similar in shape to the disc 11, is secured by a screw 39 to the block 25. The curved periphery of the disc 11 has a diameter equal to that of the bore 44 so that this disc comprises a "go" gauge whilst the diameter of the curved periphery of the disc 31 is slightly greater than that of the bore to form a "no-go" gauge. The pivoted rods enable one gauge to be used as a manipulator to tilt the other gauge as it is being moved into the bore and then to position the gauge at right angles to the bore axis at the part of the bore to be gauged. Instead of being one of the gauges, the manipulator may be a handle.