MEMOIR OF SAMUEL LEWIS PENFIELD 575 



His success as a teacher followed from his devotion to the work and his 

 personal interest in the individual student, and particularly from his 

 painstaking efforts to aid the student in every way by presenting the sub- 

 ject in the simplest manner and by assisting the imagination by ingenious 

 models and devices for illustrating crystal forms and structures. His 

 success was also due to his systematic and thorough methods of work, and 

 to a considerable extent undoubtedly to his great patience, persistency, 

 and amiability. 



That he succeeded in imparting his zeal and enthusiasm as well as his 

 skill to those who worked in his laboratory as advanced students is shown 

 by the successful mineralogists who have been trained by him. Evidence 

 of his thought and ingenuity in the arrangement of his collections and 

 apparatus is furnished by the appointments of the mineralogical labora- 

 tories in Kirtland Hall, which was built three years before his death ; and 

 it is a source of great satisfaction to his friends, as it was of happiness to 

 himself, that the last two years of his life were spent in the enjoyment of 

 his ideal of a mineralogical laboratory. 



That he fulfilled successfully his obligations as a teacher and also 

 achieved yet greater fame as an investigator was due to his extreme dili- 

 gence as a worker, devoting to his studies all of his reserve of time and 

 energy; and it was also due to his clear comprehension of mineralogical 

 problems and to his ability to execute with deftness and ease the me- 

 chanical operations required in their solution. The latter showed itself 

 in the manipulation of apparatus, whether in chemical analysis or in 

 optical or crystallographic determinations, in which he became especially 

 interested. He was for these reasons not only able to accomplish much in 

 comparatively short periods of time, and thereb}^ traverse a wide field of 

 operation, but he obtained astonishingly good results from what might 

 have proved inadequate material in less skillful hands. Some of his 

 chemical analyses were carried out successfully on very small amounts of 

 mineral, in one case upon one-tenth of a gram, and some of his crystallo- 

 graphic measurements were made on surprisingly small crystals. The 

 uniformly high quality of his work, as already said, is due to his absolute 

 honesty and conscientiousness. The exact facts and all of them that 

 could be obtained by any means at his command were the least that would 

 satisfy the demands of his nature, though of this exaction he was him- 

 self probabhr unconscioiis. It was an exaction applied to his work and 

 did not extend to his general intercourse with others, toward whom he 

 was always lenient, even indulgent. 



Much of his work was done in cooperation with others, chiefly his 

 laboratory assistants or graduate students, and he was generous in his 



