A little knowledge of mathematics has helped me, perhaps, but there isn't a thing in all this that isn't perfectly simple.

Any one of you might have found out all this for himself, without books and without a teacher.

It only requires you to think a little and to use your eyes.

Besides you've all done the same thing many a time." "I'll _bet_ I never did," said Billy Bowlegs.
"Yes you have, Billy, but you did it without thinking about it." "When ?" "Whenever you have shot a rifle at anything." "How ?" "By taking aim.

You look through one sight over the other and at the game, and you know then that you've got it in a line with your eye and the sights.