REPORT OF THE SECRETARY. 79 



J. S. JUillor, of the division of volcauic geology. From an investigation 

 of the waters of the Yellowstone National Park, made by Messrs. Gooch 

 and Whitfield, it is learned that all the hot waters of that region con- 

 tain arsenic in qnite appreciable quantities. Mr. Gooch having been 

 elected professor of chemistry in Yale College, has severed his connec- 

 tion with the Survey. 



In the physical laboratory Messrs. William Hallock and Carl Barus, 

 the latter assisted by Prof. Strouhal, of Prague, have continued i)hys- 

 ical investigations. Dr. Barus studied the internal structure of steel, 

 and he and Dr. Hallock jointly investigated the constancy of tempera- 

 ture attainable in metallic vapor baths and constructed apparatus for 

 the convenient calibration of thermoelectric pyrometers. 



Division of Mining Statistics and Technology. — Since the last report 

 was made another volume on the mineral resources of the United States 

 has appeared under the direction of Mr. Albert Williams, jr., chief of 

 this division. Somewhat fuller than its predecessor, it has been in much 

 greater demand. While these volumes record with great care the pro- 

 duction of minerals in the United States for each year, the accompany- 

 ing text relating to the various industries is different in character from 

 volume to volume. 



Mr. Williams having resigned, Dr. D. T. Day, of the Johns Hopkins 

 University, has been placed in charge of this work. 



Division of Forestry. — Since the date of the last report a division of 

 forestry has been established in the Geological Survey, and Mr. George 

 W. Shutt placed in charge thereof. Field investigations have been 

 made of the forestry of Virginia, North Carolina, and Kentucky, and a 

 large amount of material that has been received from volunteer observ- 

 ers in response to inquiries is in course of preparation for publication 

 by the Survey. 



Division of Illustrations. — Mr. W. H, Holmes, in charge of the divis- 

 ion of illustrations, presents a detailed report of the work which has been 

 done under his direction. In his administrative report for the year end- 

 ing June 30, 1885, he discusses the various methods employed for the 

 production of illustrations, and the most judicious ways of applying them. 

 During the two years covered by his administrative reports illustrations 

 have been transmitted through him for three monographs, two annual 

 reports, and eighteen bulletins. 



Division of the Library and Documents. — From the reports of Mr. C. 

 C. Darwin, chief of this division, it is learned that there has been a 

 steady and very considerable growth in the library, and that satisfac- 

 tory progress has been made in the work of cataloguing. The facilities 

 for exchange have been increased, and the rapid growth of the library 

 is due almost entirely to this feature. Although no attempt is made to 



