36 



J. D. HARDY ON AN IMPROVED COMPRESSORIUM. 



The mode of using this compressor is as follows : — The plate C 

 is first turned down into place, and the distance that it is desired the 

 glasses should be apart roughly adjusted by means of the screw /. 

 The plate C may then be turned back, and the object placed on 

 the lower glass ; the covering plate is then again turned down and 

 secured by turning the button D over it. By means of the two 

 screws d and/, the pressure can now be regulated with the greatest 

 nicety without any risk of damaging or losing the object under 

 examination. 



This arrangement admits of the glasses being easily cleaned and 

 readily replaced by new ones when broken. 



