WEDGE GAUGE. 



Ill 



effected in various ways, by means of 

 Wedge gauges. 



Lever multiplying arrangements. 

 Micrometer microscopes. 

 Optical multiplying devices. 



62. Wedge Gauge. The method of using the wedge 

 gauge is shown on Fig. 43. Here A B is a test bar whose 

 length between two points C and D requires to be measured. 



I 



u 



FIG. 43. 



Clips E and F are fixed to the bar at these two points. Of 

 these, E terminates in a flat square end, and the other one, 

 F, in a pointed end. Between these two the gauge G is 

 inserted. As the bar stretches these two ends are separated, 

 and the gauge can be pushed further in. If the slope of 

 the gauge is one in ten, a horizontal movement of the 

 gauge of one inch will correspond to a vertical movement 

 of tne points of the clips of one tenth of one inch. The 

 graduations are on the upper edge of the gauge, and the 

 slope of the gauge being one in ten, the smallest reading 

 which can be taken is a tenth of the smallest division on 



