THE HOME UNDER THE GROUND

One of the first things Peter did next day was to measure Wendy
and John and Michael for hollow trees. Hook, you remember, had
sneered at the boys for thinking they needed a tree apiece, but
this was ignorance, for unless your tree fitted you it was
difficult to go up and down, and no two of the boys were quite
the same size. Once you fitted, you drew in [let out] your
breath at the top, and down you went at exactly the right speed,
while to ascend you drew in and let out alternately, and so
wriggled up. Of course, when you have mastered the action you
are able to do these things without thinking of them, and nothing
can be more graceful.