xxxiv Address of Mr J. W. Clark, President, 



After the meeting Mr Willis exhibited a series of experiments on the trans- 

 verse and longitudinal vibrations of strings, membranes, and solids, illus- 

 trative of the researches of M. Savart. 



March 21, 1831. 



By Will. Hallows Miller, M.A. ( Joh.) : On the elimination of the time from the 



differential equations of the motion of a point, whether affected by a 



resisting medium, or by any disturbing forces. 

 By the same : On measurements of the angles of certain artificial crystals. 

 After the meeting Mr Willis exhibited and explained a machine constructed 



for the purpose of illustrating the motion of the particles of any medium 



in which undulations are propagated. 



April 18, 1831. 



By Professor Whewell : On the mathematical exposition of some of the leading 

 doctrines of Mr Bicardo's Principles of Political Economy and Taxation. 



By Professor Airy : Notice of an apparatus constructed under his direction by 

 Mr Dollond, and of the phenomena of elliptically polarized light exhibited 

 by means of the apparatus. Trans, iv. 199 — 208. 



After the meeting Professor Henslow exhibited a series of appearances pro- 

 duced by two wheels revolving one behind the other. 



May 9, 1831. 



By Ch. Pritchard, B.A. (Joh.) : A method of simplifying the demonstration of 



the two principal theorems respecting the figure of the earth considered 



as heterogeneous. 

 By Professor Whewell : On the mathematical exposition, etc. (concluded). 



Trans, iv. 155—198. 

 After the meeting Mr Willis exhibited apparatus illustrating the nature of 



sound, and the vibrations which produce it, especially an instrument 



which he calls a Lyophone. 



May 16, 1831. 



By Ja. Francis Stephens : Description of Chiasognathus grantii, a new Luca- 

 nideous insect forming the type of an undescribed genus, together with 

 some brief remarks upon its structure and affinities. Trans, iv. 209 — 216. 



By Professor Clark : On a monster of the kind called semidouble. Trans, iv. 

 219—255. 



After the meeting Mr Willis exhibited Mr Trevelyan's experiment on the 

 rocking of a bar of hot brass placed upon a plate of cold lead. 



Mr Leonard Jenyns gave an account of the application of the quinary system 

 of Mr M c Leay to the classification of Birds. 



November 14, 1831. 



By Professor Airy : On some new circumstances in the phenomena of 



Newton's rings. Trans, iv. 279—288. 

 By Professor Henslow : On a hybrid plant between Digitalis purpurea and D. 



lutea. 

 After the meeting Professor Sedgwick gave an account, illustrated by sections, 



of the geological structure of Caernarvonshire. 



November 28, 1831. 



By Leonard Jenyns, M.A. (Joh.): A monograph of the British species of bivalve 

 mollusca belonging to the genera Cyclas and Pisidium. Trans, iv, 289 — 

 312. 



