138 
POPULAR SCIENCE REVIEW. 
For young people who are short-sighted the use of spec- 
tacles should be considered imperative ; and, if the far point be 
not nearer the eyes than ten inches, these spectacles should 
generally neutralise the short sight completely. For this pur- 
pose their focal length in inches should be equal to the distance 
of the far point. If this point be nearer than ten inches, the 
eyes will generally require special advice and management. 
But in any case it must be remembered that the object of the 
spectacles is not to enable the patient to see better, but to see 
at a greater distance ; so that the book, or the writing, or the 
work, may he kept away from the eye, and the injurious effects 
of looking at a near point may be prevented. When short 
sight is increasing, there will be a constant tendency, in spite 
of spectacles, to bring the book up, and to bring the head doivn ; 
and this tendency must be fought against as the worst of all 
temptations. If yielded to, it strains the eyeballs, contracts 
the chest, overfills the head and eyes with blood, produces 
increase of the defect, and often eventual blindness. In order 
to keep the head well away, it is absolutely necessary to have 
plenty of light; and young people and students should pay 
special attention to this matter. Beading by fire-light, or in a 
window by the waning light of evening, should be strictly pro- 
liibited ; and attention should be given to the quality of artificial 
light. For lighting up a room, there is perhaps no light 
superior to that of a paraffine lamp with two parallel wicks ; * 
and the best table light for reading or writing is afforded by 
the well-known lamp made by Stobwasser of Berlin, and com- 
monly known as the “ Queen’s Beading Lamp.” It should 
have a green shade, and should be just so much lowered that 
this shade protects the eyes, when they are raised from time to 
time, from the direct glare of the flame. 
The flat or hypermetropic e}"e is a great source of trouble to 
its possessor ; and until quite recently this trouble was in- 
curable 1)}^ any known means. As has been explained, the flat 
eye is never at rest. It is always using some of its accommo- 
dation, often using all. Ifence it becomes speedily fatigued, 
and, with fatigue, the accommodation relaxes, and vision 
Ijecornes dim. The hypermetropic person will begin to read or 
to write witli ease. After a short time the eyes feel strained 
and tired, and the letters become misty. Tlie patient looks 
away from his work, shuts Ids eyes, presses the hand upon tlie 
closed lids with a very peculiar gesture, and makes a fresh 
start. The second period of work is shorter than the first, 
and the tliird sliortcr than the second. This affection was long 
known as “asthenopia” or “weak sight,” and jus its cause was 
• rnlcntoil hy Ilinks of Birniingbani. 
