191 
SCIENTIFIC SUMMARY. 
ASTRONOMY. 
I T cannot be said that anything very unusual has taken place in astrono- 
mical matters since our last summary. We have little to record in the way 
of discovery or research. More perhaps has been done in preparation for 
what is to come^ and the great eclipse of the sun on the 17th of August 
next claims the foremost place. A very long period will most probably 
elapse before so long an interval of total obscuration of the sun’s light will 
again occur j it is not surprising, therefore, that preparations on a large and 
complete scale are now in progress for taking advantage of an event which 
may prove, if the weather be favourable, of the greatest utility in eluci- 
dating the phenomena of the solar photosphere. On the occasion in ques- 
tion, the moon will be but six hours from its perigee, while the sun will be 
near its apogee : a combination of circumstances which increases the ap- 
parent diameter of the former, and lessens that of the latter. Owing to this 
the darkness will be of more than usual duration, indeed, at some points in 
the path of the shadow it will continue for nearly seven minutes. A very 
complete chart of the path of the eclipse has been issued by the Nautical 
Almanac office, with diagrams of the solar disc, at various places on the line 
of shadow, giving the points on the sun’s limb where the first and last con- 
tact will take place; also the Greenwich mean time of the* middle of the 
eclipse at these places. From near Aden, the central line extends to the 
southern coast of New Guinea, crossing Hindostan, the Bay of Bengal, the 
Malayan Peninsula, and the Gulf of Siam. M. Leverrier recommends, as 
the south-west monsoon will be blowing at the time, rendering observations 
somewhat uncertain, on account of clouds, except on the east of mountain 
ranges, that some of the French vessels, in the Gulf of Siam, should search 
for a suitable place on the eastern side of the Malayan Peninsula, in which 
to make a complete series of observations. With regard to England, two 
well-equipped expeditions have already proceeded to India, for observing the 
eclipse. That originated by the Royal Astronomical Society will be con- 
ducted by Major Tennant, who has gained a large amount of experience in 
solar photography from Mr. Be la Rue ; he will be assisted by some of the 
men of the Royal Engineers, who, through the kindness of Mr. Be la Rue, 
have been through the whole process of taking the negatives, enlarging, 
&c., at his observatory at Cranford. A reflecting telescope, of the New- 
tonian form, will be used for photographic purposes, while, for stereoscopic 
and polarising experiments, the telescope of the society, lately employed by 
Mr. Hewlett, has been fitted with the necessary apparatus. The other 
