"Yes," answered the Professor laughing. "It is rather a heavy weight to bear, but a solid arch spans over our heads. The great Architect has built it of the best materials; and never could man have given it so wide a stretch. What are the finest arches of bridges and the arcades of cathedrals, compared with this far reaching vault, with a radius of three leagues, beneath which a wide and tempest-tossed ocean may flow at its ease?