MEMORIALS OF J. FRANCIS WILLIAMS. 457 



investigation led him in 1889 to take the position of honorary fellow at 

 Clark university, Worcester. While in this relation he received over- 

 tures from Professor J. C. Branner which led to his undertaking the de- 

 scription of the igneous rocks of Arkansas. Dr. Williams secured leave 

 of absence from Clark and entered on his Arkansas work as a volunteer 

 without salary in October, 1889. In the summer of 1890 he was made 

 honorary docent at (lark university. This title, like his previous one, 

 carried no salary with it, and merely afforded him a work-room and 

 headquarters. Dr. Williams gave some lectures on crystallography to 

 chemists during one or two months in the spring, and for this purpose 

 furnished his own models, diagrams, etc, and even loaned his own goni- 

 ometer to the chemical department of the university for whatever meas- 

 urements were made on crystallized salts. 



Dr. Williams found a wealth of interesting material in Arkansas, and 

 as the result of his collecting published in 1890 the papers on mangano- 

 pectolite and eudialyte cited below. In the fall of 1890 he returned to 

 Arkansas and completed his work, remaining, except for one or two trips 

 home, until the summer of 1891. He had meantime accumulated the 

 observations for his final and greatest work, which forms volume ii of 

 the annual report of the Arkansas geological survey, and is entitled 

 "Igneous Rocks of Arkansas." The volume, which is just distributed, 

 contains 432 pages, 391 of which are by Dr. Williams alone, and which 

 uive an accurate and exhaustive petrographic description of the syenites 

 eleolite-syenites and leucite-syenites, the variations of all three, and the 

 basic dikes which pierce them. Perhaps the greatest interest lies in the 

 identification of leucite in these rocks and in the establishment of Creta- 

 ceous leucite-syenites as a new variety. This opposes the generally held 

 but quite unwarranted belief that leucite is limited to the later volcanic 

 rocks. The report is accompanied by beautifully executed topographic, 

 maps and by many other illustrations. Much of its success was made 

 possible by the cordial and efficient support given Dr. Williams by Pro- 

 fessor Branner, but it bears on every page the marks of tireless and pains- 

 taking scholarship. Professor Branner in the preface bears testimony to 

 the enthusiasm and energy with which Dr. Williams carried it through, 

 mid the writer of this memorial, who was associated in some minor por- 

 tions of the work, can witness also to his consuming interest in his work. 

 Dr. Williams was appointed assistant geologisl Oil the survey in 1891, 

 and in this official capacity his name appears on the title page of the 

 report. In L 891, in connection with Dr. Et. N. Brackett, he carried on 

 investigations in certain minerals of the Kaolin group, which appeared 

 in the American Journal of Science in July last. 



