Page:Popular Science Monthly Volume 44.djvu/621

Rh, and do not break them down. The walls of this exterior enceinte are hollowed by galleries of two kinds: some horizontal and giving access from outside to all the stories, the others mounting spirally in the thickness of the wall to the summit of the dome. When the colony is in full activity, after the construction is completed, these little passages have no further use. They served for the passage of the masons when building



the cupola, and they could be utilized again if a breach should be made in the wall. At the lower part these galleries in the wall are very wide, and they sink into the earth beneath the palace to a depth of more than 1·50 metre.

These subterranean passages are the catacombs of the Termites, and have a very close analogy with those of old and populous human cities. Their origin is similar; they are ancient quarries. The insects hollowed them in obtaining the necessary