Small though we made them on paper, these two- hundred-foot moons were still too much for us. Of course we meant to build them hollow. But even if hollow there must be some thickness, and the quantity of brick would at best be enormous. Then, to get them up! The pea- shooter, of course, was only an illustration. It was long after that time that Rodman and other guns sent iron balls five or six miles in distance,--say two miles, more or less, in height. Iron is much heavier than hollow brick, but you can build no gun with a bore of two hundred feet now,--far less could you then. No. Q. again suggested the method of shooting oft the moon. It was not to be by any of your sudden explosions. It was to be done as all great things are done,--by the gradual and silent accumulation of power. You all know that a flywheel--heavy, very heavy on the circumference, light, very light within it--was made to save up power, from the time when it was produced to the time when it was wanted. Yes? Then, before we began even to build the moon, before we even began to make the brick, we would build two gigantic fly-wheels, the diameter of each should be "ever so great," the circumference heavy beyond all precedent, and thundering strong, so that no temptation might burst it. They should revolve, their edges nearly touching, in opposite directions, for years, if it were necessary, to accumulate power, driven by some waterfall now wasted to the world. One should be a little heavier than the other. When the Brick Moon was finished, and all was ready, IT should be gently rolled down a gigantic groove provided for it, till it lighted on the edge of both wheels at the same instant. Of course it would not rest there, not the ten-thousandth part of a second. It would be snapped upward, as a drop of water from a grindstone. Upward and upward; but the heavier wheel would have deflected it a little from the vertical. Upward and northward it would rise, therefore, till it had passed the axis of the world. It would, of course, feel the world's attraction all the time, which would bend its flight gently, but still it would leave the world more and more behind. Upward still, but now southward, till it had traversed more than one hundred and eighty degrees of a circle. Little resistance, indeed, after it had cleared the forty or fifty miles of visible atmosphere. "Now let it fall," said Q., inspired with the vision. "Let it fall, and the sooner the better! The curve it is now on will forever clear the world; and over the meridian of that lonely waterfall,--if only we have rightly adjusted the gigantic flies,--will forever revolve, in its obedient orbit, the-- BRICK MOON,