the plan. "Suppose one over the meridian of Greenwich,
and the other over that of New Orleans. Take care that
there is a little difference in the radii of their
orbits, lest they `collide' some foul day. Then, in most
places, one or other, perhaps two will come in sight. So
much the less risk of clouds: and everywhere there may be
one, except when it is cloudy. Neither need be more than
four thousand miles off; so much the larger and more
beautiful will they be. If on the old Thornbush moon old
Herschel with his reflector could see a town-house two
hundred feet long, on the Brick Moon young Herschel will
be able to see a dab of mortar a foot and a half long, if
he wants to. And people without the reflector, with
their opera-glasses, will be able to see sufficiently
well." And to this they agreed: that eventually there
must be two Brick Moons. Indeed, it were better that
there should be four, as each must be below the horizon
half the time. That is only as many as Jupiter has. But
it was also agreed that we might begin with one.

Why we settled on two hundred feet of diameter I
hardly know. I think it was from the statement of dear
John Farrar's about the impossibility of there being a
state house two hundred feet long not yet discovered, on
the sunny side of old Thornbush. That, somehow, made
two hundred our fixed point. Besides, a moon of two
hundred feet diameter did not seem quite unmanageable.
Yet it was evident that a smaller moon would be of no
use, unless we meant to have them near the world, when
there would be so many that they would be confusing, and