Vol. XXIV. No. 6.] 
POPULAR SCIENCE NEWS. 
93 
Tlie value of this admirable treatise on chemistry 
is evident by the quick succession in which the edi- 
tions follow each other; and, in fact, for a general 
work on all the different branches of the science, 
this will easily rank among the foremost. It is fully 
brought up to date, and — es])ecially in the depart- 
ment of organic chemistry — many important changes 
and additions have been made. 
The same firm publish A A'ew Medical Dictionary, 
by George M. Gould, M. I)., a compact volume of 
about 500 pages, but which, nevertheless, contains 
full definitions of all the words and phrases usually 
met with in medicine. While equally useful with 
the more bulky works of a similar character, its 
greater convenience and lower price will commend 
it to all. 
» 
Electric Light fnstallaiions and the Management of 
Accumulators., by Sir David Solomons, C. E. 
Published by D. Van Noslrand Co., New York. 
Electrical accumulators, or storage batteries, are 
constantly coming into more extended use, and, 
although the absurd predictions first made in regard 
to them have not been realized, they have a definite 
and prominent place in electrical technology. This 
is the first book published that is entirely devoted to 
the subject, and is written by a most eminent author- 
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valuable work. 
Practical Mining, by John G. Murphy, E. M. Pub- 
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Investments in mining stock have an unenviable 
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Encyclopedia of the Manufactures and Products of 
the United States. The Seeger and Guernsey Co., 
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This is one of the most comprehensive commer- 
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Ifow to Preserve Health, by Louis Barkun, M. D. 
American News Co., New York. 
A Perfect Memory : How to Attain It, by John A. 
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York. 
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Epitomes of Three Sciences : Comparative Philology, 
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Patriphlets, etc., received : The Chemistry of Bone 
Charcoal, by Dr. Alfred K. Glover, Grand Haven, 
Mich. ; Transactions of the Kansas Academy of Sci- 
ence; I'uhlications of the l.ick Observatory, Mount 
Hamilton, California; Enucleation of the Eyeball, 
by J. Hobart Egbert, M. D. ; .Tournal of the Klisha 
Mitchell Scientific Society, Chapel Hill, N. C. ; 
Beport of the Illinois State Board of Health, and 
the Circulars of the U. S. Bureaus of Education and 
Statistics. 
n^edicirje and Pljarnjacy. 
[Original in I'opular Science A'ews.] 
THE CARE OF THE EYES. 
Captain Marryatt has justly said : "A man may 
damn his own eyes, but has no right to exercise a 
similar prerogative over other people's visual 
organs ; " and, while we shall not presume to 
"damn" at all, we shall endeavor to lead those who 
are suffering from remediable ocular defects — endur- 
ing the inconvenience, the headaches, and other 
afflictions which such defects occasion — to conduct, 
as it were, their visual organs through the courts of 
retributive justice, so that if they have given trouble, 
they may not only be sworn at, but also indicted, 
condemned to trial, and sentenced to proper correc- 
tion. 
Throughout life, from youth to old age, there is a 
process of change occurring in the refractive media 
of all eyes, so that everyone who attains to a ripe 
old age will, at some time or other during his or her 
existence, be a fit subject for the oculist — or, in 
other words, will need to wear glasses. In young 
people this change is usually gradual and unper- 
ceived, but from middle life onward its effects are 
plainly apparent. Those who have normal vision 
while young will require glasses for reading when 
they have passed beyond the age of forty, and those 
who are near-sighted before this age is reached, 
need glasses in early life, if the degree of near- 
sightedness (myopia) be at all great, and yet they 
may be able to read perfectly well without glasses 
when fifty, or even sixty years of age. Persons 
who are included in this category are apt to consider 
thetnselves as lucky exceptions to general laws, and 
are usually very proud of their sharp sight. 
But not only does the eye undergo certain normal 
changes as age advances, but it may be abnormally 
formed; and hence optical defects are not only pos- 
sible, "but quite common in infants. The eye is a 
camera, and, while it may be free from disease and 
perfectly sound, still vision may be bad because the 
rays of light are not focused upon the retina. 
Hence comes the necessity for wearing glasses, for, 
by placing suitable lenses before these eyes, normal, 
distinct vision may — within certain limits — be ob- 
tained. It is not generally known that it is the 
exception, and not the rule, to find eyes that are 
perfect in shape, or, technically speaking, that are 
"emmetropic." Still it does not follow that all 
eyes that are not perfect in shape should have 
glasses fitted to them, for some errors of refraction 
do not interfere seriously with vision, and nevdr 
give rise to disease or decided discomfort to the 
patient; but, as a rule, persons whose eyes are 
"weak," or who suffer from complaints similar to 
those which we shall soon consider, should present 
themselves to some competent oculist for the detec- 
tion and subsequent correction of any existing 
errors of refraction. Let me briefly say that by 
"competent oculist" is meant one who has not only 
a knowledge of the delicate mechanism of the eye, 
but of the other organs of the body as well ; for 
abnormalities and diseases of the eye link them- 
selves very closely to diseased conditions of other 
portions of the physical economy. Consequently, 
the competent oculist is a doctor of medicine, 
although he may devote himself entirely to the 
study and practice of ophthalmology. The jeweler 
and the peddler are not proper persons to fit glasses ; 
and, while it is true that certain opticians are con- 
scientious enough to send the party to an oculist 
when they find that they cannot correctly fit a 
patient with glasses, still there are opticians who 
are less conscientious, and who, lest the acknow- 
ledgment of incapacity might lower their standard 
in the public mind, or cause the loss of a customer, 
advise glasses which are not correct in every 
respect. Moreover, the oculist has means at his 
command for the detection of errors of refraction 
which cannot be applied by the optician, and pos- 
sesses a knowledge of the proper correction of these 
errors which 3 ears of study and experience can 
alone bestow. 
There still exists quite a prejudice in the minds of 
many against the use of glasses, but why such 
prejudice should exist is very difficult of explanation 
on any other grounds than wilfulness and igno- 
rance. All ophthalmologists teach the great neces- 
sity of correcting errors of refraction by wearing 
proper glasses, and we shall herein endeavor to 
show some of the undesirable, and even portentous 
results of permitting optical defects to go uncor- 
rected. As a rule, glasses add nothing to the 
appearance of the wearer, and they are often a 
source of inconvenience, and, unless there is a 
definite object to be attained by their use, patients 
are better without them ; but where they are indi- 
cated and advised by one competent to decide, 
neither vanity nor prejudice should prevent their 
being employed. 
The purposes for which glasses should be pre- 
scribed may be briefly summed up thus : First, to 
prevent disease of the eyes from "eye strain;" 
second, to aid in the curing of certain diseases and 
abnormal conditions, by releasing all strain and 
giving the eyes rest; third, to enable the patient to 
better pursue his avocation in life; and fourth, for 
his comfort and convenience. Our consideration 
of these items must necessarily be brief and, conse- 
quently, imperfect. The first two are of paramount 
importance, and aftbrd material for many chapters 
in the study of refraction. In general, it may be 
said that all errors of refraction which reduce the 
patients' vision to any extent below the normal, or 
which produce any marked change in either the 
near or the far points, require correction by the use 
of suitable glasses. These errors are; hyperopia, 
or far-sight; myopia, or near-sight; presbyopia, or 
old-sight ; and astigmatism,, or irregular sight. 
Let us first consider the dangers from hyperopia. 
There is a constant strain, known as "an effort of 
accommodation," upon every far-sighted eye wherr 
viewing both near and remote objects. This effort 
of accommodation is a muscular exertion, and hence 
a tax upon the nervous system, and, if long con- 
tinued, results in more or less exhaustion. When 
far-sighted eyes are used for reading or near work, 
for any considerable period of time, the effort re- 
quired produces congestion and redness of the eyes, 
a larger flow of blood is seht to them, and hence 
there is an increased secretion of mucus, or " water- 
ing of the eyes ; " and, if the work be still continued, 
dizziness, headache, a feeling of sickness, or even 
actual vomiting, may be induced. But in far- 
sighted children another condition not infrequently 
arises as soon as they are made to apply themselves 
to books. The child begins to have a cast in the 
eye — that is, to squint or look " cross-eyed." At 
first the squint may be periodic, and appear only 
when close work is undertaken, but, unless means 
are employed to prevent it, it soon becomes perma- 
nent. In the great majority of cases, internal 
squint is due to hyperopia. An excessive effort of 
accommodation is always associated with increased 
convergence, and, as a far-sighted eye must alwavs 
increase its accommodation in order to gain clear 
vision, it naturally squints inward. Nervous 
twitchings of the eyelids and other portions of 
the face are sometimes occasioned by hyperopia. 
Fortunately, the condition of hyperopia can be 
easily corrected by suitable convex spherical glasses, 
and thus the conditions of weariness and exhaustion 
