_William_.--(Smiling rather contemptuously.) "Poor sister! Whatignorance!"

_Father_--"William, speak kindly--tell your sister what thisinstrument is, and what you want to do with it."

_William._--(Scientifically.)--"In war, when a besiegedgarrison wishes to know all the movements of the enemy, without beingseen, they erect close behind the walls, or the ramparts, a mirror, placedat the end of a long pole, and inclining towards the country. Youunderstand, then, that everything that takes place outside, isreflected in the mirror, and can be seen from within, or in anothermirror placed at the bottom of the pole, and sloping inwards. This,Lucy, is what is called a polemoscope--that is to say, an instrumentfor observations in war."