REPORT OF THE PRESIDENT, 1918. 9 



has not arrived; no chapter concerning them is yet complete; 

 most of them are still in the stages of development, while some 

 of them have been only recently inaugurated. The work in 

 question is involved with and is evolving with many concomitant 

 activities of governmental departments and other organizations, 

 so that the activities of the Institution and its staffs are not imme- 

 diately and obviously separable. Moreover, much of this work 

 is of a confidential nature, concerning which the Government is 

 not only entitled to current control but to precedence in historical 

 record. But while this is neither the time nor the place for a full 

 account of these unusual occupations of the Institution, it appears 

 not inappropriate and not untimely to cite two of them, drawn 

 from widely separated fields of investigation, which have led to 

 results of international as well as national importance and which 

 help, in ways popularly unexpected but rationally predictable, 

 to justify the existence of research estabhshments. These two 

 cases may serve to indicate the kinds of work in which the staffs 

 and associates of the Institution are now engaged and to show 

 how easy it is to pass from what appear to be abstract investiga- 

 tions to the most concrete and utihtarian apphcations of them. 



To men of science it was well known two years prior to April 



1917 that the United States would encounter a serious shortage of 



optical glass if compelled to resort to arms in the 



Production of .n ■•• n- i c l^ 1 1 ^ ' 



Optical Glass by rapidly expanding conflict; for there would be im- 

 Laboratory! mediately needed large numbers of telescopes, field 

 glasses, gun-sights, range-finders, periscopes, and 

 other optical adjuncts, without which the ordnance departments 

 of the Army and Navy would be myopic if not bhnd. Provision 

 for this emergency was forecast by both the National Research 

 Council and the Naval Consulting Board. It was known to 

 them that the Geophysical Laboratory of the Institution had 

 made special studies of siUcates during something hke a decade 

 before the date referred to, and that in staff and in determinative 

 appUances this was probably the best-equipped estabUshment in 

 existence to make the preliminary investigations and to furnish 

 the superintendence in manufacture essential to the develop- 



