SCOUTING FOR GIRLS 
263 
A knapsack strapped on to the shoulders is not only 
more convenient because it leaves the arms and hands 
free to swing naturally or use for other purposes, but 
because the weight is distributed and is carried by means 
of heavy muscles pushing up under the strap. A weight 
should be distributed over a set of muscles as evenly as 
possible, and this is the reason for suspending a knapsack 
from two shoulders instead of one, when possible. 
Finally, in doing any sort of lifting or pulling, if the 
muscles that are to be used are contracted before grasp- 
ing the weight they will be able to do their work with 
far less effort. Try lifting a small weight like a book in 
two ways — first, have your hand and fingers relaxed 
and limp when you grasp it, and see how heavy it seems 
and how hard it is to contract your muscles properly 
while lifting it. Then drop the book and go at it again, 
this time anticipating its weight and contracting your 
hand and finger muscles before grasping it. See how 
easily it comes up. Try this same thing with heavier 
weights, and learn always to contract the muscle before 
taking the load. In carrying a weight for any distance 
it is well to shift it from one arm to another, always 
preparing the muscles by contracting them before the 
weight is assumed. 
Using the muscles so as to take advantage of their 
lever-like qualities in the best way, contracting them be- 
fore loading, and pushing instead of pulling, go to make 
up what is sometimes called ‘‘getting a purchase.” 
4. Supply Daily Need, for Air , Sun , Water and Food 
— Besides exercise and rest there are other controllable 
factors upon which health depends. These are air, heat 
and light of the sun, water and food. To grow and work 
properly the body needs plenty of each of these. 
Air — If you cannot work or play outdoors you can 
still bring out of doors in by opening your windows at 
