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SUMMARY OF CURRENT RESEARCHES RELATING TO 
of the instrument it is provided with a knee-joint below the stage, and 
an arrangement has been designed by means of which the pillar rotates 
on the base, reversing the position of the stand on the foot (fig. 40) 
so that stability is maintained in all positions. The stage is firmly fixed 
and is not liable to flexure. The body-tube has the standard screw and 
