476 Prof. Tyndall on Calorescence. [Nov. 23 



The proposal having been seconded, the ballot was taken, and Mr 

 Villiers was declared duly elected a Fellow of the Society. 

 Mr. Villiers was afterwards admitted into the Society. 1 



The following communications were read : 



I. "On Calorescence." By JOHN TYNDALL, F.R.S. 

 Received October 20, 1865. 

 (Abstract.) 



The paper is divided into ten short sections. In the 1st the experiments 

 of Sir William Herschel and of Prof. Miiller on the sun's radiation are 

 described. In the 2nd are given a series of measurements which show the 

 distribution of heat in the spectrum of the electric light. In the 3rd 

 section is described a mode of filtering the composite radiation of an in- 

 tensely luminous source so as to detach the luminous from the non-lumi- 

 nous portion of the emission. The ratio of the visible to the invisible 

 radiation determined in this way is compared and found coincident with 

 the results of prismatic analysis. The eminent fitness of a combination of 

 iodine and bisulphide of carbon as a ray-filter is illustrated, and in the 4th 

 section experiments with other substances are described ; various effects 

 obtained in the earlier experiments on the invisible rays being mentioned. 

 In the 5th section the absolutely invisible character of the radiation is 

 established ; it is also proved that no extra-violet rays are to be found at 

 the obscure focus. Numerous experiments on combustion produced by 

 invisible rays are also described in the 5th section. The 6th section 

 deals with the subject of calorescence, or the conversion of obscure radiant 

 heat into light. In section 7 various modes of experimenting are described 

 by which the danger incident to the use of so inflammable a body as the 

 bisulphide of carbon may be avoided. In the 8th section are described 

 experiments on the invisible radiation of the lime-light and of the sun. In 

 the 9th section the effect obtained by exposing papers of different colours 

 at the dark focus are mentioned ; while the 1 Oth and concluding section, 

 deals with the calorescence obtainable from rays transmitted by glasses of 

 various kinds. 



II. " Notice of the Surface of the Sun." By JOHN PHILLIPS, M.A. 

 LL.D., F.R.S., &c., Professor of Geology in the University of 

 Oxford. Received October 27th, 1865. 



It appears desirable, as a first step to a right theory of the condition of 

 the sun's surface, that the appearances which it presents should be re- 

 corded in some systematic way. Photographs will suffice for the distribu- 

 tion of the spots, but careful eye-drawings must be appealed to in evi- 

 dence of the form, arrangement, and intestine motions of the parts of those 

 spots, and eye-drawings with measures are the only means of recording 

 accurately the dotted, areolar, granular, crested, and other arrangements 



