Meetings held during the Session 1898 — 1899. 187 



May 15th, 1899. 



Mr J. Larmor, President, in the Chair. 



The text of an address to Sir George Gabriel Stokes, conveying 

 the Congratulations of the Society on the occasion of his Jubilee, was 

 read from the Chair. 



The following Communications were made : 



1. Mr J. J. Lister exhibited larvpe of Branchipus and Estheria 

 reared from dried mud. 



2. Notes on the Binney Collection of Fossil Plants. II. A new 

 type of Palaeozoic Plant. By Mr A. C. Seward. 



3. On the modification and attitude of Idolum diabolicum, a 

 Mantis of the kind called Floral Simulators. By Dr D. Sharp. 



4. On the product J m (x) J n x. By Mr W. M C F. Orr. 



June 5th, 1899. 



In the Cavendish Laboratory. 



Mr J. Larmor, President, in the Chair. 



This was a Special Meeting of the Society for the presentation of 

 papers to be published in a volume commemorative of the long con- 

 nexion of Sir G. G. Stokes with the Society. 



The following papers were communicated : 



1. On the analytical representation of a uniform branch of a 

 monogenic function. By Professor M. G. Mittag-Leffler. 



Prof. Mittag-Leffler gave an account of the scope and aim of his 

 paper. 



2. The theory of groups. By Professor H. Poincare\ 



3. Ueber die Bedeutung der Constante b des van der Waals'schen 

 Gesetzes. Yon Prof. Boltzmann und Dr Mache, in Wien. 



4. By Professor A. Righi. 



5. On the echelon spectroscope. By Professor A. A. Michelson. 

 Prof. Michelson exhibited and described his new spectroscope, and 



used it to demonstrate the Zeeman effect. 



