280 A CENTURY OF SCIENCE 



rate use of this projection in solving problems in 

 crystallography. 



Penfield was born in 1856, was graduated from the 

 Sheffield Scientific School in 1877 and immediately 

 became an assistant in the chemical laboratory of that 

 institution. At this time he, together with his colleague 

 Horace L. Wells, made the analyses of the minerals from 

 the newly discovered Branchville locality. He spent the 

 years 1880 and 1881 in studying chemistry in Germany, 

 returning to Yale as an instructor in mineralogy in the 

 fall of 1881. Except for another semester in Europe at 

 Heidelberg he continued as instructor and professor of 

 mineralogy in the Sheffield Scientific School until his 

 early death in 1906. 



It is difficult to choose for mention the names of other 

 investigators in Mineralogy during this period. Toward 

 its end a great many writers contributed to the pages of 

 the Journal, more than fifty different names being 

 counted for the volumes 41 to 50 of the Third Series. 

 Many of these are still living and still active in scientific 

 research. Mention should be made of Frank W. Clarke, 

 who contributed many important articles concerning 

 the chemical constitution of the silicates. His work on 

 the mica and zeolite groups is especially noteworthy. 

 The work of W. H. Hillebrand, particularly in regard to 

 his analytical investigations of the minerals containing 

 the rarer elements, was of great importance. The name 

 of W. E. Hidden should be remembered, because, with 

 his keen and discriminating eye and active search for new 

 mineral localities, he was able to make many additions to 

 the science. 



In glancing over the indices to the Journal the close 

 interrelation of mineralogy to the other sciences is strik- 

 ingly shown by the fact that so many scientists whose 

 particular fields are along other lines have published 

 occasional mineralogical papers. Frequently a young 

 man has commenced with mineralogical investigations 

 and then later been drawn definitely into one of these 

 allied subjects. Men, who have won their reputation in 

 chemistry, physics, and all the various divisions of geol- 

 ogy, even that of palaeontology, have all contributed arti- 

 cles distinctly mineralogical in character. For this 



