742 



SCIENCE 



[N. S. Vol. XXXVIII. No. < 



greater the ionization. This relation is shown 

 graphically in the following curves, where No. 

 I. shows the mean ionization produced by the 

 yS and y rays as compared with the ionic 

 charges and No. II. shows the same relation 

 for the a radiation. 



Fernando Sanford 

 Stanford Universitt, 

 September 30, 1913 



SCIENTIFIC BOOKS 



THE MARYLAND DEVONIAN BOOKS 



The fine series of volumes issued by the 

 Maryland Geological Survey (Professor Wm. 

 Bullock Clark, state geologist) has recently 



1 Maryland Geological Survey : Lower Devo- 

 nian. Text, 560 p.; Middle and Upper Devonian. 

 Text, 719 p.; Plates (Lower Devonian, 1-98; 

 Middle Devonian, 7-44; Upper Devonian, 45-73). 

 Baltimore, The Jolins Hopkins Press, 1913. 



been substantially supplemented in number and 

 enhanced in worth by the publication of what 

 may, for brevity, be styled the " Maryland 

 Devonian Books."'^ 



Following the tasteful pattern and admira- 

 ble mechanical execution of the previous 

 members of the series, the Devonian books 

 constitute a graceful and enduring monument 

 to the scientific vigor of the State of Maryland 

 in which His Excellency, The Honorable 

 Phillips Lee Goldsborough, and his distin- 

 guished colleagues of the Geological Survey 

 Commission may take a just and satisfying 

 pride. These books are three stout volumes 

 and the golden device of the state which they 

 carry on their covers declares that good men 

 have done this work at the command of the 

 presiding genius of Maryland. The accom- 

 plishment of this undertaking is the fulfilment 



