REVIEWS. 
497 
OPTICAL DEFECTS OF THE EYE * 
T he literature of ophthalmology will soon he something ponderous. 
Here is another treatise upon eye-surgery. It is written by Mr. 
J. Z. Laurence, one of the surgeons to the Surrey Ophthalmic Hospital, 
and a gentleman well known for his devotion to this department of surgery. 
The volume is not pretentious, and is little more than a reprint of lectures 
which some time ago appeared in the pages of the Medical Times and Gazette. 
It calls, therefore, for little notice at our hands. We like the method which 
the author has adopted in constructing his optical diagrams. The employment 
of cones of rays is a decided improvement upon the old system, under which 
either the axis of the pencil or the extreme ray was alone represented. If 
all writers upon optics would pursue the plan Mr. Laurence has followed, 
’twould be an intense relief to the unhappy student. It seems to us that 
in some cases the author is rather too forcible in his denunciations of views 
from which he differs. W e cannot at all agree with him in saying. 
The theory that the cornea changes its convexity is one of those traditions 
that, devoid of all demonstrated truth, has (sic) still retained its hold on 
some conservative minds.” 
His explanations of the abnormal conditions, known as myopia, hyperme- 
tropia, presbyopia, asthenopia, and astigmatism, are, so far as we have been 
able to examine them, clearly and accurately rendered. Whether Mr. 
Laurence’s treatment is in every instance orthodox, of course time alone can 
determine. We wish his book all the success it deserves. 
APPLIED GEOLOGY.f 
npO those who fancy that Geology is a species of abstract science we coin_ 
mend the little volume which Professor Ansted has just given us. It 
is the report of a series of lectures which this eminent geologist delivered 
before the Society of Arts, and is written in the Professor’s clearest style. 
Dividing his subject into six sections, the writer touches upon the several 
applications of geological knowledge to the arts and industry. First, we 
have a chapter on agricultural geology ; then we are told all about the science 
of and laws regulating springs and water-supply ; and, in the other “ Lec- 
* “ Optical Defects of the Eye, and their Consequences : Asthenopia and 
Strabismus.” By John Zachariah Laurence, F.K.C.S., M.B. Univ. of 
London. Hardwicke. 1865. 
t “ The Applications of Geology to the Arts and Manufactures, &c.” By 
Professor D. T. Ansted, M.A., F.K.S. London : Hardwicke, 1865. 
