360 Samuel Lewis Penfield. 



raphy, but also in astronomy, geodesy, navigation, etc. He pre- 

 pared also an ingenious set of instruments for use in connection 

 with this method of projection by means of which laborious 

 calculations could be avoided and the problems quickly and 

 accurately solved by graphic methods. He extended these 

 practical methods and applied them to the drawing of crystals, 

 devising special plates of axes to be used in connection with his 

 instruments by which the solving of the form of a crystal and 

 the drawing of its figure could be easily and rapidly carried out. 

 These methods have since come into very general use. . 



In reviewing Penfield's work in mineralogical science one is 

 struck, not more by its quantity than by its quality and varied 

 aspects. He was a thoroughly trained man and had a firm grasp 

 on every phase of his subject. He had a wide and accurate 

 knowledge of minerals and the correctness with which he often 

 identified them at sight seemed almost like intuition. While 

 he clearly apprehended principles and, as has been shown, pro- 

 duced generalizations of wide importance, the great majority of 

 his contributions to science are not of a theoretical nature but 

 consist of direct and positive additions to knowledge. He had 

 a highly analytical mind, and this combined with his inventive 

 faculty and the great manual skill with which he was gifted 

 made him a born investigator, one of the greatest who has yet 

 appeared in his field of science. It is safe to say that with his 

 gifts he would have had a successful career in whichever of 

 the physical sciences he might have entered. The thoroughness 

 of Penfield's work, its high quality and the completeness with 

 which he covered every side of his subject, is well illustrated 

 in his last paper on stibiotantalite, published in the current 

 July number of this Journal, in conjunction with his junior 

 associate and former pupil Professor Ford. 



His services to science have been worthily recognized at 

 home and abroad : in 1893 he was made an associate Fellow of 

 the American Academy of Arts and Sciences in Boston : in 1896 

 he became a Foreign Correspondent of the Geological Society 

 of London and his university conferred on him the degree of 

 Master of Arts : in 1900 he was elected a member of the 

 National Academy of Sciences : in 1902 he was chosen as a Fel- 

 low of the American Association for the Advancement of Sci- 



