1822.] Analyses of Books. 293 
the houses seemed to melt a highly attenuated frosty vapour in 
the air, and in this heated medium, the spires were situated. 
In the month of July, the same year, I observed a perpendi- 
cular elongation of faintly reddish light from the setting sun to 
the clouds. Its breadth was equal to the sun’s diameter. 
The western sky was covered with clouds, except an opening 
round the sun 15° high, and 12° wide. The departing rays, as 
is usual in this country in summer, coloured the edges of the 
clouds, wherever they penetrated, a scarlet red; and from the 
unevenness of the surface, gave the illuminated parts the appear- 
ance of flame. 
This elongation of light appeared to extend forward nearly to 
the observer. The place where I stood was on rising ground 
near the town; at about half a mile in front was the river Oupa. 
In the vapour rising from the river, and the dampy holm on this 
side of it, originates this elongation of the sun’s figure. 
ARTICLE IX. 
ANALYSES OF Books. 
Memoirs of the Astronomical Society of London. Vol. I. 
London. 1822. 
(Concluded from p. 153.) 
The second of the three memoirs furnished by the Rey. William 
Pearson, is entitled, ‘‘ On the Construction and Use of a Mi- 
crometrical Eye-piece ofa Telescope.” The rationale of the new 
contrivance is given, previously to explaining the application 
of the doubly-refracting power to some of the most delicate 
measurements in practical astronomy ; but this preliminary disqui- 
sition, which is extended to a considerable length, not admitting 
of intelligible abridgment, nor indeed bearing very materially 
on the subject, we shall proceed to give Dr. Pearson’s account 
of the application of this power. ‘ In measuring the diameter of 
a small body of sensible dimensions, the sliding tube containing 
the prism must be steadily and gradually moved by the finger 
and thumb, backwards or forwards, until after adjustment for 
good vision, the two images of the object come exactly into 
contact, edge to edge: in this situation the distance indicated, 
will be the argument for entering the table of powers ; and the 
power there seen by inspection, will be the proper argument for 
entering the table of measures, which will give at sight the appa- 
rent diameter, in seconds and parts of a second, without further 
correction. When the angular distance between two stars, 
satellites, or other luminous points, is required to be measured, 
