CONTENTS. 
PAGE 
Art. I. On the Life and Writings of Commandant 
Emile Le Puillon de Boblaye. By M. Rozer, 193 
II. Comparative Remarks on the Recent and Fossil 
Mollusca of the South of Italy, and more par- 
3 ticularly of Sicily. By Dr ‘A. Purziprt, 202 
I. Comparative number of the Mollusca of the pre- 
sent epoch, and of the Tertiary Period, ; 203 
II. Relative numbers of the Extinct and ots 
Species, : s 5 204 
III. Physiognomy of the Mollusca of the Tertiary 
Period and of the present day, 3 210 
IV. What is the proportion of the Living and Ex- 
tinct Species at the individual localities? Have 
all the latter a like age? Can subdivisions be 
established in the Tertiary formation of South- 
ern Italy; and if so, what are they? . Ae PAY 
III. On admitting the Back-Light, in Portable Dio- 
ramas, upon different parts of a Picture at 
different times; on using Light from Oil, 
&c. By Georce Tait, Esq., F.R.S.S.A. 
Communicated by the Royal Scottish Society 
of Arts, ; : : : - 214 
IV. Description of the Great Chimney at St Rollox, 
Glasgow, and of the Climbing- Machine used 
in examining and repairing a Rent in that 
Chimney at the height of 280 feet. By Lewis 
D. B. Gorpon, Esq., Professor of Civil-En- 
gineering in the University of Glasgow, and 
