Notices of Books. 
527 
876.] 
dealing with the matter, the rays of a direcft pencil refracted 
through a lens would be regarded as convergent or divergent, 
according as the aberration was towards or from the second 
surface of the lens, which we submit to be an entirely new view 
of convergency and divergency. Having, by reasoning satis- 
factory to himself, demonstrated the existence of a lunar atmo- 
sphere having probably about 1 - 300th part of the surface 
density of our atmosphere, Mr. Neison states that such an 
atmosphere is “ not incapable of exerting as powerful influences 
on the surface as the earth’s,” and this because “ its mass in 
proportion to that of the planet is only a little less than a fourth 
of that of the earth’s, and with regard to even a single square 
mile in area of the surface, must be estimated by millions of 
tons.” But in what way the largeness of the total mass of the 
atmosphere, or the pressure on a square mile of lunar surface, is 
to compensate for the fact that the surface density and pressure 
are certainly very minute, he in no way attempts to show. If 
the atmospheric pressure could be reduced anywhere on the 
earth till the mercurial barometer stood at one-tenth of an inch, 
the amount of air somewhere else, or the fact that even this 
reduced pressure was equivalent to some goo millions of tons on 
the square mile, would not in the slightest degree tend to make 
that attenuated air equal in influence to air 300 times as dense. 
The chapter relating to the history of lunar research is fairly 
accurate. Towards the close, however, Mr. Neison refers to the 
work done under the auspices of the British Association without 
mentioning the fact, that this work gave so little promise of 
leading to anything of value that the British Association with- 
drew its support. It is the general opinion of astronomers that 
the outlay of the Association was entirely thrown away. 
The chapter on variations of the moon’s surface contains little 
that has not been said elsewhere ; but there is one passage 
relating to the supposed changes of the floor of Plato which is 
certainly incorredt. After describing these changes, Mr. Neison 
says that they are not “ due to the effedts of contrast, remaining 
unaffedted when these are eliminated.” The exadt reverse is 
the case. 
The next section, which indeed forms the bulk of the work, is 
occupied by descriptions of twenty-two maps. These remind 
us of Madler’s large map reduced in surface more than 
one half, cut up into twenty-two parts, and modified by omissions 
and additions, the law of which we fail to recognise. Some 
details are added which only the possessors of powerful telescopes 
could hope to examine with advantage, others are omitted which 
can be easily seen with a three inch objedt-glass. But the great 
mistake has been the division of the chart into many parts and 
the introduction of 3-into a cumbrous volume. The seleno- 
grapher does not want a book of maps, still less a large volume 
in which such maps are accompanied by a quantity (in this case 
