CONTENTS. 
I. Additional observations on the optical properties and structure 
of heated glass and unannealed glass drops. By David 
Brewster, LL. D . F. R. S. Edin. and F. S. A. Edin. In a 
Letter addressed to the Right Hon. Sir Joseph Banks, Bart. 
K.B.P.R.S. p. i. 
II. Description of a new instrument for performing mechanically 
the involution and evolution of numbers. By Peter M. Roget, 
M. D. Communicated by William Hyde Wollaston, M. D. 
Sec. R. S. 9. 
III. Experiments on the depolarisation of light as exhibited by 
various mineral, animal , and vegetable bodies, with a reference of 
the phenomena to the general principles of polarisation. By 
David Brewster, LL. D. F. R. S. Edin. and F. S. A. Edin . 
In a letter addressed to the Right Hon. Sir Joseph Banks, Bart. 
K. B. P. R. S. 29. 
IV. On an ebbing and flowing stream discovered by boring in the 
harbour of Bridlington. By John Storer, M. D. Communi- 
cated by the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S. 
54 * 
V. On the effects of simple pressure in producing that species of 
crystallization which forms two oppositely polarised images , and 
exhibits the complementary colours by polarised light. By 
David Brewster, LL.D. F. R. S. Edin. and F. S. A. Edin. In 
a letter addressed to the Right Hon. Sir Joseph Banks, Bart. 
K. B. P. R. S. p. 60, 
