8 REPOKT OF THE SECEETARY. 



The report of the research on the spectrum conducted by Dr. Victor 

 Schumann, of Leipzig, has received extensive additions during the year, 

 notaldy through a detailed description of the ingenious apparatus used 

 in his work. This supplement is accompanied ]\v illustrations which 

 appear now for the first time, although Dr. Schiunann has been author- 

 ized to announce in the scientific journals of his own country the dis- 

 coveries made in the course of his experiments, at the same time 

 notifying the In.stitution of his progress. 



A second grant on l)ehalf of Dr. Schumann has l)een approved dur- 

 ing the 3'ear, and it is interesting to know that Harvard Universit}^, 

 recognizing the value of his work, has also awarded him a grant. The 

 new Physical Institute of the Royal Academy of Sciences in Leipzig 

 has likewise aided this research by placing laboratory room at the dis- 

 posal of Dr. Schumann, who, it is hoped, will ])e able in the near 

 future to secure still more complete results from his painstaking 

 experiments in vacuum spectroscopy. 



The memoir by Dr. Carl Barns, mentioned in my last report as in 

 course of publication, has been issued during the jeav as part of Vol- 

 ume XXIX, Smithsonian Contributions to Knowledge. It describes 

 experiments with ionized air begun ))v Dr. Barus some years since 

 and iccently prosecuted imder a Ilodgkins grant from the Institution. 

 The research was tributary to an investigation of the colors of cloudy 

 condensation. Lord Rayleigh's famous theory, if applied, would stop 

 at the deep reds of the first order, terminating in opaque, whereas in 

 the ]:i])orator3' experiments exceptionally brilliant colors, extending 

 almost into the third order of Newton's series, may ])e produced. It 

 was thus essenti;»1 as a preliminary step to investigate appropriate 

 means for the ]uo<hiction of nuclei, to determine their number per 

 cubic centimeter, their velocity, their association with ionization, the 

 effect of the pressure of an electric field, etc. This was the general 

 trend of the experiments by Dr. Barus. The endeavor was made with 

 the aid of tlie condensation tube to show that the nucleus has a specific 

 velocity of it>^ own, and that this is retained even in the absence of an 

 electi'ic ti(d(l. The application of this principle to plate, to tubular, 

 and to sph(*iii-al condensers leads, in (nery case and in spite of the 

 variation of method, (o an order of Aalues as to the number of parti- 

 cU's in action. agrcH'ing witii the data obtained by other investigators 

 from diffei'ent experiments and th(M)retically different ])oints of view. 



A second grant has ])een api)roved on beiialf of Dr. Barus, and a 

 new memoir on the structure of the nucleus, detailing experiments 

 subsecjuent to tliose descril)e(l in the \<)hime just pu1)]ished is soon to 

 be submitted l)y him. 



The experiments in air resistance ))y Mr. C. Canovetti, referred to 

 in the Secretary's last report, which were begun at Brescia, Italy, of 



