476 
THE NERVOUS SYSTEM OF MAN 
(see page 406). This tube is a trifle more than an inch 
long. When it becomes closed, partial deafness results. 
Defects in hearing may be caused by blows upon the 
ears, by the accumulation of wax in the ears, and by sore 
throat. When there is a continued ringing or hissing sound 
in the ears, consult a doctor 
at once. 
385. Brain Efficiency. — 
While the efficiency of the 
brain depends upon mental 
training, in order properly to 
exercise the many functions 
of this organ at least three 
things are necessary: good 
food, sufficient sleep, and 
abstinence from alcohol and 
tobacco. We have already 
discussed the question of 
food (page 410). 
The amount of sleep which 
grown people need depends 
in part upon the kind and 
amount of work they do. 
But all young people require 
a large amount of sleep. 
Children from seven to ten years of age need at least twelve 
hours of sleep every night, while youths of high school age 
need at least nine hours, and ten would be better. 
At a baseball game, you have noticed a boy catch a “ fly ” 
when it looked like a “ home run/’ or how enthusiastic 
the crowd became when the pitcher struck out the last 
man with the bases full. The nervous system of both players 
was efficient in a critical test. 
We all ride on the street cars or railroads, but do you 
know that most of the men who run the street cars and 
SKILL AND ENDURANCE IMPAIRED 
BY DRINK 
Tests in Target-Shooting in Swedish Army 
I. SKILLED TESTS 
Thirty shots fired in quick succession 
Non-Drinking Days: Average 24 hits out 
of 30 shots 
Drinking Days: Average 3 hits out of 
30 shots 
Alcohol taken equal to amount in to 2 
pints of 5 per cent beer, 20 to 30 minutes 
before shooting, and an equal amount the 
night before 
II. ENDURANCE TESTS 
Non-Drinking Days: 360 shots fired be¬ 
fore exhaustion 
Drinking Days: 278 shots fired before ex¬ 
haustion 
Alcohol taken 30 minutes before test was 
amount contained in about 1*4 pints of 
4 per cent beer 
Figure 419. 
