13 



study. There are at present about one thousand rock sections 

 with the collections. 



The instruction of Mr. Wolff consisted of lectures twice a 

 week, and laboratory work. The course was attended by seven 

 students throughout the year, and to others instruction was 

 temporarily given. 



Mr. Wolff's own work has been a study of the altered sedi- 

 ments represented by the gneissic rocks of the Green Mountains, 

 in connection with three summers of field-work in that region. 

 The results are interesting in their bearing on metamorphism. 



