Nature, "1 

 7, 1920J 



Nature 





A WEEKLY 



[LLUSTRATED JOURNAL OF SCIENCE 



VOLUME CV 



MARCH, 1920, to AUGUST, 1920 



To the solid ground 

 Of Nature trusts the mind which builds for aye." — Wordsworth 



//♦'/ 



Jon Don 



M A C M 1 L L A N AND CO., Limited 



NEW YORK: THE MACMILLAN COMPANY 



