Telescoping inside gage instrument

Claim 1

IN A TELESCOPING INSIDE GAGE INSTRUMENT TO BE INTRODUCED INTO A BORE AND THENCE INTO AN UNDERCUT GROOVE ON THE FACE OF THE BORE TO MEASURE THE DIAMETER OF THE GROOVE, THE COMBINATION OF A TUBULAR CASING WITH A HANDLE EXTENDING LATERALLY THEREFROM, TWO GAGE PINS PROJECTING BEYOND THE ENDS OF SAID CASING, SAID CASING HAVING GUIDE MEANS TO ENABLE THE PINS TO SLIDE TO AND FRO, SPRINGS CORRESPONDING RESPECTIVELY TO THE PINS FOR YIELDINGLY BIASING SAID PINS TOWARD THEIR EXTREME OUTWARDLY EXTENDED POSITIONS, ONE OF SAID SPRINGS BEING RELATIVELY WEAKER THAN THE OTHER; AND FIXING MEANS INCLUDING A SCREW-ACTUATED PART FOR ENGAGING THE SIDE OF THE PIN HAVING THE WEAKER SPRING, SAID SPRINGS BEING COIL-TYPE SPRING, AND THE PIN HAVING THE RELATIVELY STRONGER SPRING ALSO HAVING A SOCKET IN ITS INNER END RECEIVING THE END OF THE WEAKER SPRING FOR CENTERING THE SAME.