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POPULAR SCIENCE REVIEW. 
THE SUPPOSED NEW CRATER ON THE MOON. 
By E. Neison, F.R.A.S. 
N EAR the centre of the surface of the lunar hemisphere 
which is turned towards the earth, there is an open region 
which is called by astronomers the Mare Vaporum. It is a 
tolerably level plain, with a grey coloured surface, broken by some 
small hills and craters, and traversed by a number of low, gently 
sloping ridges. It is bordered on all sides by elevated hill 
lands, plateaux, or lofty ridges. This region is from its situa- 
tion so favourably placed for observation that all its features 
can be observed and its appearance delineated with great 
facility. 
In the southern portion of this grey plain, the Mare Va- 
porum, there is a small crater some five miles in diameter, which 
was named Hyginus by Riccioli, the founder of the present 
system of lunar nomenclature. The crater lies in the centre of 
a level portion of the Mare Vaporum separated from the rest by 
some broad valleys and ridges of a dark grey colour. Running 
right across the plain a. very remarkable formation was dis- 
covered by Schroter, the celebrated Hanoverian astronomer and 
the rival of Sir William Herschel. This formation, which is 
termed a cleft or rill, resembles a great dry canal or gorge, or 
still more what is in America termed a Canon. It is a sharply 
marked gorge or ravine over a thousand feet deep, and about three- 
quarters of a mile broad, with steeply falling sides. It extends 
for nearly 1 50 miles right across the plain, bursting through all 
obstacles, and ending on the great grey plain called the Mare 
Tranquillitatis. This rill was the first of these extraordinary 
formations which was discovered, so that its discovery excited 
much astonishment and led to the entire region being examined 
with great care. Since then many similar though more minute 
formations have been discovered, and in particular a most intri- 
cate system of these rills was discovered by Beer and Madler 
in the open plain to the south of Hyginus. In consequence of 
these discoveries this portion of the lunar surface has been most 
