

MEMOIRS i»''^"',1.wlf" 



Sectional Lsbtcay 



OF THE 



NATIONAL ACADEMY OF SCIENCES 





.^e^T^^rO^^ 





V^^'^^ -^r^S^l 



Voliame XII 



gecv-cv-^- 



P»art II 





SECOND ]yj_tUM:OIR 





WASHINGTON 

 1915 



