If it be accepted that Mr. So-and-so may set up stakes, fence off sections of this boundless earth, and register that area as his own, what is to prevent such persons from roping off blue sky, from staking claims on heaven, an enclosure of the air? If natural law permitted proprietorial parceling-out of the land and its sale and purchase at so much the square foot, then it would also permit partition of the air we breathe at so much the cubic unit and its three-dimensional sale. If, however, it is not proper to trade in sky, if enclosure of
