/ Nat 



Sature, 1 ^ 



April u, I9»IJ ^ 



Nature 



A WEEKLY I ^^AY 4 1921 



ILLUSTRATED JOURNAL OF SCIENCE 



VOLUME CVI 



SEPTEMBER, lyao, to FEBRUARY, 1921 



'' lo the solid ground 

 Of Sature trusts the mind which builds for o^*."— Wordsworth 



.1 





I' 



JlonOoit 

 MACMILLAN AND CO.. Limitbd 



NKW YORK: THK MACMII.I.AN f;OMPANY 



