778 SUMMARY OF CURRENT RESEARCHES. 



a variety of pyroxene, as it had always been supposed. Cleavage frag- 

 ments of the mineral measured by a hand goniometer also readily 

 showed the prismatic cleavage to be that of amphibole. 



Fay, H., Higgins, A. W., and Cobuen, F. W. — Study of the Relations between 

 the Microstructure, the Heat Treatment, and the Physical Properties of Axle 

 Steel. Technology Quarterly, XVI. (March 190;;) pp. 4-17, 15 figs. 



ISeokek, A — Krystalloptik. Eine ansfuhrliche elementare Darstellung aller wesent- 

 lichen Erscheinungen, welche die Krystalle in der Optik darbieten. nebst einer 

 historisehen Entwicklang der Theorien des Lichtes. 



Stuttgart, 1903. 362 pp. and IOC figs. 



