Intelligence and Miscellaneous Articles. 535 



a common magma of normal basaltic type, and that, by the 

 upward passage of gases through the magma, a relative con- 

 centration of the alkalies took place in its upper part, which 

 was the earliest erupted. It is further suggested that the intense 

 decomposition of the spilites is a case of auto-metamorphism, 

 due to retention of volatile constituents resulting from the physical 

 environment of a submarine flow. 



An analogue to the radiolarian cherts and jaspers, generally 

 associated with spilites in other localities, is found in Derbyshire 

 in the quartz-rock and other siliceous rocks that frequently occur 

 in proximity to volcanic vents. 



Since the spilites appear to be differentiates from a normal 

 basaltic magma, resulting largely from their physical environ- 

 ment, it is concluded that they do not form a separate suite of 

 igneous rocks distinct from other alkaline rocks. 



O 



LIU. Intelligence and Miscellaneous Articles. 



ARNOLD LQCKHART FLETCHER. 



N April the 30th Arnold Lockhart Fletcher died at Eouen 

 of severe wounds received in action. He was in the 28th year of 

 his age. During his short life he accomplished work of permanent 

 value. 



Arnold Fletcher was educated in various schools in England 

 and Ireland, and entered Trinity College, Dublin, in 1906, He 

 graduated in Arts and in Civil Engineering, obtaining the latter 

 degree in 1909. Shortly after passing his finals in Engineering 



he was appointed Assistant in the Department of Geology a 



subject in which he had displayed a keen interest as a student. 

 During his tenure of this post the work of research in this 

 Department was mainly confined to the distribution of radioactive 

 elements. Most of Fletcher's papers are devoted to this subject. 

 Various important materials were examined by him, using, at first 

 the method introduced by Strutt, and, later, the method by fusion! 

 When a convenient means of estimating thorium emanation was 

 devised, the search for this element was added to that of radium 

 emanation. 



Fletcher's papers on the radioactivity of rocks and minerals show 

 him to be an enthusiastic worker who spared no pains to 

 obtain reliable results. His paper on the radium content of 

 Secondary Hocks well illustrates his minute care in research 

 (Phil. Mag. Feb. 1912). This paper will, in the present writers 

 opinion, Ions; remain the best work which has been clone on these 

 materials. Indeed it cannot be superseded, for it is a record of 

 natural quantities which enter as essential data into geological 

 science, and must retain its value unless some at present unknown 

 source of error can be shown to exist. 



This and several of his other papers show Arnold Fletcher as 

 possessed of the most valued quality of the investigator the de- 

 termination to arrive at accuracy. But they also show him to be 

 possessed of the inventiveness which continually improves upon 



