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



May 7, 1821. 



By Joh. Fre. Will. Herschel, M.A. (Joh.) : On the refraction of Apophyllite. 



Trans. I. 241—247. 

 By Professor Sedgwick : On the geology of the Lizard (concluded). Trans. I. 



291—330. 



May 21, 1821. 



By Professor dimming : On the connexion between galvanism and magnetism. 



Trans. I. 281—286. 

 By Will. Cecil, M.A. (Magd.) : On the application of regulators to machinery. 



November 12, 1821. 



The following communication from Dr Brewster was read by Prof. E. D.' 

 Clarke : 



" I have examined with great care a specimen of Leelite, and I find it 

 to be an irregularly crystallized body, like Hornstone, Flint, and having a 

 sort of quaquaversus structure, or one in which the axes of the elementary 

 particles are in every possible direction, instead of being parallel, as they 

 must be in all regular crystals. The alumina which Leelite contains gives it 

 quite a different action upon light from any of the analogous siliceous sub- 

 stances ; and I have thus obtained an unerring optical character by which 

 Leelite may be distinguished from them with the greatest facility. 



In examining the different kinds of topazes, I have found that the colour- 

 less topazes, and the blue topazes of Aberdeenshire, differ not merely from the 

 yellow Brazil topazes, but also from one another." 



Signed, D. Brewster. 

 By Mr Okes : On a peculiar case of an enlargement of the ureters in a boy of 

 eleven years of age. Trans, i. 351 — 358. 



November 26, 1821. 



By Fre. Thackeray, M.D. (Emm.) : On a remarkable instance of organic 



remains found on the turnpike road between Streatham and Wilburton 



in the Isle of Ely. Trans, i. 459. 

 By Will. Mandell, B.D. (Qu.) : On an improvement in the common mode of 



procuring potassium. Trans. I. 343 — 345. 

 By Will. Whewell, M.A. (Trin.) : On the crystallization of fluor spar. Trans. 



I. 331—342. 

 By Joh. Stevens Henslow, M.A. (Joh.) : On the geology of the Isle of 



Anglesea. 



December 10, 1821. 



By Professor Cumming : On a remarkable human calculus in the possession 



of the Society of Trinity College. Trans, i. 347—349. 

 By Joh. Stevens Henslow, M.A. (Joh.) : On the geology of the Isle of 



Anglesea (continued). 

 By Ch. Babbage, M.A. (Pet.) : On the use of signs in mathematical reasoning. 



(Ptead by Mr Peacock.) Trans, n. 325—377. 



February 25, 1822. 



By Joh. Hailstone, M.A., late Fellow of Trin. Coll., and Woodwardian Pro- 

 fessor : Some observations on the weather, accompanied by an extra- 

 ordinary depression of the barometer, during the month of December, 

 1821. (Read by the Secretary.) Trans. I. 453—458. 



