18. _Test of Strength of a Bow._--What is the test of the strength of a
_bow_?
Does the distance the bow throws the arrow increase in ratio to its
strength?
What was the length of the bows used in the good old times? _Were the
bows then made of more than one piece?_ Is there any advantage in having
bow of _more_ than _two_ pieces?
What wood _were_ the _arrows_ made of?