134 LUCY AMONG THE MOUNTAINS.

But Lucy could not understand how any thing
could be contrived to let the water come up, and
then keep ‘it from going down. Robert told her
about the upper box and the lower box; but he
did not succeed in making it plain to her. In
fact, it requires considerable skill in the art of
describmg and explaining, to communicate any
clear idea of the internal construction and working
of a pump. Lucy could not get any idea of it
whatever. She asked her mother to explain it to
her; but her mother said that she did not under-
stand it very well herself. So Lucy said she did
not know what she should do.

The road led them, for a time, along the shores
of the pond, and generally not much above the
water. And, as they passed along, they could
see the water on one side of them, and sometimes
they had forests, and sometimes steep rocks, on
the other. At length, they came to a place where
Lucy proposed that they should stop and eat
their luncheon. It was a place where a brook
flowed into the pond. The road crossed the
brook by a bridge, just above its juncture with
the pond ; so that, when they were on the bridge,
they could see the pond below them, between
the steep banks of the ravine, through which the
brook flowed. One of the banks was an almost
perpendicular cliff of rock. The other was not
quite so abrupt, and it was covered with trees.
They could.see that down upon the shore of the
pond, there was a smooth, sandy beach, extending
along the shore on each side of the mouth of the
brook. Lucy proposed that they should stop here.