526 
Notices of Books. 
[October, 
produce such a treatise. He has gone overground already well- 
trodden, and while his book has thus been so enlarged as to be 
as costly as Mr. Nasmyth’s, it has been deprived of the special 
qualities which would have made it valuable to selenographers. 
It is, in faCt, a general treatise on the moon. 
The first chapter deals with the motions, figure, and dimen- 
sions of the moon ; the second with her physical condition ; the 
third with the various lunar formations ; the fourth with what 
the author calls “ lunar history,” meaning thereby the history of 
lunar research ; the fifth with the variations of the moon’s 
surface ; the sixth introduces the description of illustrative maps, 
to which the seventh, and many following chapters relate in 
detail; and the last chapter presents a number of formulas, seleno- 
graphical and otherwise. The chapter on the motions, figure, 
and dimensions of the moon is not satisfactory. For the most 
part, Mr. Neison quotes the descriptions given by French and 
German mathematicians. In some cases, by the way, he does 
not translate these descriptions correCtly, as, for instance, at 
page 6, where the word “ remplacer,” used in the sense of 
“ taking the place of,” is represented by the English word 
“ replace,” which has quite a different, and, in this case, a quite 
incorrecft sense. 
In describing the motion of the lunar perigee, Mr. Neison 
writes, “ The direction of the semi-axis major is not constant, 
but undergoes a slow revolution, the period of which is 8*8505 
years, and in the same direction as the motion of the moon in 
its orbit, but with variable velocity, the lunar perigee being 
occasionally before and then behind its mean place.” This 
description is incorreCt. The motion of the perigee is not 
always in the same direction as the motion of the moon in her 
orbit and variable only in velocity. It varies in direction also, 
being sometimes progressive and sometimes retrogressive ; ad- 
vancing, on the whole, because the progressions are greater than 
the retrogressions. The reverse is the case with the motion of 
the nodes, which alternately retreat and advance, but on the 
whole retreat; whereas Mr. Neison describes this motion also as 
simply varying in velocity. The second chapter, on the moon’s 
physical condition, is more original, but, apart from errors 
respecting physical laws, there is one remarkable error relating 
to a subjeCt which Mr. Neison claims to have studied with 
special attention — the optical laws, namely, in which the refrac- 
tive aCtion of an atmosphere depends. “ It may be remarked,” 
he says, “ that the rays, after traversing any atmosphere to the 
moon, would not be convergent as in a lens, but, owing to the 
refraction diminishing rapidly with the distance from the surface 
would be truly divergent ; for the rays refraCted by each spherical 
shell of atmosphere, as it were, of indefinably small thickness, 
would reach a different focus,” According to this novel way of 
