3o8 Mr. Haldane Gee and Dr. A. Harden on 



being placed between the two tubes. (Another instru- 

 ment, in which the stereometer tube consisted of a wide tube 

 sealed on to a graduated and calibrated stem, was first 

 -employed, but did not give quite such good results). The top 



Fig. 6. 



of tube A was ground, and could be closed by a small plate 

 of ground glass, which was covered with a thin layer of a 

 mixture of vaseline and bees' wax. By unscrewing the 

 clamps, and adjusting the tube A at the bottom of the stand, 

 the instrument also could be employed with increase of 

 pressure. 



