230 
POPULAE SCIENCE EEYIEW. 
Tomlinson’s curious researches on cohesive figures have been in part 
introduced, and that Graham’s discovery of dialysis is described. We have 
not seen any allusion to his atmolytic investigations, hut we presume they 
appeared too late for insertion. The pages devoted to spectral analysis 
embrace everything that has been done upon the subject, and contain even 
reference to Plucker’s discovery which was not announced till last April. 
Tyndall’s researches are carefully detailed, and the chapters on static and 
voltaic electricity are all that could be desired. The style is clear and 
forcible, and the woodcuts are numerous and well-executed. As a text- 
book, Dr. Miller’s volume is unquestionably the best of its kind, and must 
be read by the student of natural philosophy ; whilst, at the same time, 
we think it well worthy the perusal of serious non-professional readers. 
S old age steals upon man, not only is “ his natural strength ” abated, 
but his powers of vision are impaired, and his eyes become dim. 
This ocular obscurity may be the result of one or more of several distinct 
alterations of the structure of the organs of sight. Some warn us of their 
approach by reason of their effects, others are more stealthy in their pro- 
gress. Some are attended almost invariably with a partial or total impair- 
ment of the visual sense, others are comparatively harmless. To the second 
and fourth categories belongs the class of ophthalmic disease upon which 
the excellent monograph just published treats. “Arcus Senilis” is the title 
of Mr. Canton’s book. What is Arcus Senilis ? Literally, it means the old 
man's bow; and surgically, it is a term applied to a disorganized crescentic 
structure which appears in old age at the borders of the transparent portion 
of the eyeball. This phenomenon is produced by a degeneration of the 
healthy tissue, which gives place to a quantity of oily matter devoid of 
transparency. Hence, it is also termed “ fatty degeneration of the cornea.” 
We think Mr. Canton’s quotation from Paget’s writings ill-advised ; it is 
merely a thoughtless jest at. the expense of our modern school of com- 
parative anatomists, and we allude to it only because he has selected it to 
ornament the first page of his beautiful memoir. Waiving this, w T e do not 
grudge our praise to almost every other portion of the work. The history 
of the malady justifies the opinion that the author is as thoroughly 
master of this branch of the subject as his great reputation proves him to 
be in every other. The pathology of the cornea has been carefully studied, 
and is illustrated by reference to both original and borrowed engravings 
In this department due attention has been bestowed on the opinions of 
the German and French schools of ophthalmologists ; and although the 
objectives employed have been of comparatively low magnifying powers, 
yet the structure, or absence of structure, has been tolerably well revealed. 
The lithographic plates are good, but not as perfect as they might be. The 
cases appended are admirably recorded, fully confirm the author’s views, 
* “ On the Arcus Senilis, or Fatty Degeneration of the Cornea.” By 
Edwin Canton, F.R.C.S., President of the Medical Society of London, &c. 
London : Hardwicke. 1863. 
DISEASES OF THE EYE.* 
