187 
PHYSICAL AND MATHEMATICAL SECTION. 
March 28th, 1871. 
E. W. Btnney, F.R.S., F.G.S., President of the Section, 
in the Chair. 
Mr. Brothers, F.R.A.S., after some preliminary remarks 
as to the chief objects of the English Eclipse Expedition to 
Sicily, in December last, exhibited on the screen a series of 
photographs illustrating, in the first instance, the means 
adopted for obtaining photographs of the eclipse. A series 
of pictures was then shown illustrating the corona as photo- 
graphed during the eclipses in 1860, 1868, and 1869, and 
the whole of the pictures taken during the totality in 1870 
at Syracuse. These were shown in comparison with the 
pictures taken in Spain by the American observers, and 
also with sketches taken by members of the English expe- 
dition in Spain. These illustrations showed in a remarkable 
manner the advantages of photography in depicting pheno- 
mena such as are seen during eclipses of the sun— the strict 
identity of the positions of the rifts or dark spaces in the 
corona being shown most perfectly. The identity of those 
rifts was also shown by comparison with a drawing made 
by Professor Watson at Carlentini, in Sicily. 
During the evening Dr. Roscoe, F.R.S., explained the im- 
portance of spectrum analysis in investigating the solar 
phenomena, and described the preparations he had made for 
viewing the eclipse from his station on Mount Etna, about 
5,000 feet above the sea level. 
The photographs and other illustrations were exhibited 
by means of Mr. T. Harrison’s powerful electric apparatus. 
Pboceedings— Lit. & Phil. Soc. — Yol. X. — No. 17.— Session 1870-71. 
