1865.] De la Rue, Stewart, and Loewy on Solar Physics. 37 



thin for examination with very high powers if immersed in a limpid fluid. 

 The arrangement of the nerve-fihres I have referred to is not to be de- 

 monstrated in tissues immersed in water. The finer branches of the 

 nerves are in fact quite invisible until the specimen is well impregnated 

 with a highly refracting fluid. The imperfect methods of preparation 

 usually employed for examining the higher tissues have given rise to a 

 prejudice against the employment of high powers. I have not referred to 

 the use of very high powers in studying the characters of the Diatomaceee, 

 because it is a branch of microscopic investigation which I have very 

 little studied. Other observers will probably state very shortly if any- 

 thing is gained by the use of these high powers in this department. It 

 is probable that, by improved means in illuminating the objects, many new 

 and important points will be made out by the use of very high magnifying 

 powers. Mr. Brooke has already suggested possible improvements in the 

 condenser, some of which, I believe, he will carry out shortly. 



January 26, 1865. 



Major-General SABINE, President, in the Chair. 

 The following communications were read : 



I. " Researches on Solar Physics. Series I. On the Nature of Solar 

 Spots." By WARREN DE LA RUE, Ph.D., F.R.S., BALFOUR 

 STEWART, A.M., F.R.S., Superintendent of the Kew Observa- 

 tory, and BENJAMIN LOEWY, Esq. Received January 10, 1865. 



(Abstract.) 



After giving a short sketch of the history of their subject, the authors 

 proceed to state the nature of the materials which had been placed at 

 their disposal. In the first place, Mr. Carriugton had very kindly put 

 into their hands all his original drawings of sun-spots, extending from 

 November 1853 to March 1861. In the next place, their materials were 

 derived from the pictures taken by the Kew heliograph. A few pictures were 

 taken by this instrument at Kew Observatory in the years 1858 and 1859. 

 In July 1860 it was in Spain doing service at the total eclipse. In 1861 

 a few pictures were taken at Kew, while from February 1862" to February 

 1863 the instrument was in continuous operation at Mr. De la Rue's private 

 observatory at Cranford, and from May 1863 until the present date it 

 has been in continuous operation at Kew under Mr. DC la Rue's super- 

 intendence. A Table was then given, from which it was deduced that the 

 number of groups observed at Kew from June to December 1863 in- 

 clusive was 64, while that observed by Hofrath Schwabe during the 

 same interval was 69. In like manner, the number at Kew between 

 January and November 1864 inclusive was 109, while during the same 

 interval Hofrath Schwabe observed 126. It thus appears that Schwabe' s 

 numbers are somewhat larger than those of Kew ; but probably, by means of 

 a constant corrective, the one series may be made to dovetail with the other. 



