REPORT OF THE SECRETARY. 11 



PUBLICATIONS. 



Tlio Institution issued during tlie year a total of 45,506 volumes or 

 separates of the series of Contributions, Miscellaneous Collections, 

 lieports, and publications not included in the regular series." The 

 document division received for action a total of 8,522 letters and cards 

 of acknowledgment. 



In the publications of the Institution the double aim of its founder 

 is represented, in that it should exist for (1) the "increase" and (2) the 

 "diffusion" of knowledge. 



The recording of results of original researches, the " increase " of 

 knowledge, is chiefly through the series of Contributions to Knowledge, 

 a quarto work begun in 1S4S, and in which more than 140 valuable 

 memoirs, collected in 82 volumes, have so far been pu])lished. There 

 has been added to this series during the year a memoir of 190 pages by 

 Dr. Carl Barus on the Structure of the Nucleus, a continuation of his 

 experiments with ionized air, which w^ere described in a memoir pub- 

 lished during the previous year. 



In the present investigation the author answers certain practical 

 questions suggested b}" his last memoir in relation to phosphorus wdien 

 used as a source of nuclei; i. e., of extremely small particles tending 

 to precipitate water from moist air when this is suddenl}^ cooled. It 

 is, however, the chief aim of the memoir to throw light on the phe- 

 nomena connected with the presence of nuclei in air by aid of the coro- 

 nas or color rings se^n in such air when its moisture is condensed and 

 deposited on the nuclei and a distant source of light is looked at 

 through the turbid medium. As these coronas occur in great variety 

 and size they lend themselves to measurement when other means fail, 

 A systematic stud}- is therefort> made at the outset of the number of 

 particles corresponding to all well-defined members of the sequence of 

 coronas obtained under known conditions of supersaturated air. The 

 naml)ers run from less than 100 to upward of 50,000 per cubic centi- 

 meter. 



The results are then applied in an endeavor to find the velocity of 

 the nucleus by nonelectrical methods, both of a direct and an indirect 

 kind, utDizing the fact that if nuclei leave the medium the coronas 

 ol>tained under like conditions must change correspondingly, Thn >ugh- 

 out the latter part of the investigation the nuclei are purposely pro- 

 duced in the simplest manner possible, by shaking solutions in air; 

 but in the course of the investigation the author reaches conclusions 

 which seem to show that the solutional nucleus is of much broader 

 meteckrological significance in its bearing on atmospheric condensation 

 and electricity than has heretofore been anticipated. It appears that 



« Contributions to Knowledge, 1,983; Miscellaneon.s Collections, 11,667; Reports, 

 26,237; publicationw not in regular series, 5,619. 



