too dense, we could watch the progress of agriculture, and the growth of cities. If it is a world of strife, we could distinguish, on the battle-field, the colour of the uniforms of the opposing masses. All this could be accomplished by our present optical means; and, as our powers of vision increased, we could descend to the minuter details of life. We could readily conceive a code of signals by which telegraphic communication might be carried on between us and our lunar neighbours. The moon, however, sternly withholds from us her great secret, and for ever turns from us her hidden hemisphere.
Granting that the other side of the moon is peopled, can our world be ever known to the inhabitants, seeing that only the lighter side is turned toward us? It is plain that the inhabitants, if they keep to their own side, can never get a glimpse of the earth. If there is an atmosphere, it is probable that it may extend a small way within the visible side, though in a rarefied form. We can then conceive the intrepid lunar inhabitants venturing, as far as they can breathe, within the barren hemisphere; just like adventurous travellers on our globe, scaling lofty mountains, to obtain an extended view of the landscape. What an astonishing spectacle must burst upon the view of the lunar tourist, as soon as he fairly gets within the new hemisphere! The traveller, who has spent the night on the summit of the Rigi, to watch the rising of the sun over the snow-
