From every part of these large galleries are various small covert ways, or galleries leading to different parts of the building. Under ground there are a great many that lead downward by sloping descents, three and four feet perpendicular among the gravel, whence the workers cull the finer parts, which, being kneaded up in their mouths to the consistence of mortar, become that solid clay or stone of which their hills and all their buildings, except their nurseries, are composed. Other galleries again ascend, and lead out horizontally on every side, and are carried under ground near to the surface a vast distance: for if all the nests are destroyed within a hundred yards of a house, the inhabitants of those which are left unmolested farther off will still carry on their subterraneous galleries, and, invading it by sap and mine, do great mischief to the goods and merchandise contained in it. It seems there is a degree of necessity for the galleries under the hills being thus large, since they are the great thoroughfares for all the labourers and soldiers going forth or returning, whether fetching clay, wood, water, or provisions; and they are certainly well calculated for the purposes to which they are applied by the spiral slope which is given them; for if they were perpendicular the labourers would not be able to carry on their building with so much facility, as they ascend a perpendicular with great difficulty, and the soldiers can scarcely do it at all. It is on this account that sometimes a road like a ledge is made on the perpendicular side of any part of the building within their hill, which is flat on the upper surface and half an inch wide, and ascends gradually like a staircase, or like those winding roads which are cut on the sides of hills and mountains, that would otherwise be inaccessible; by which and similar contrivances they travel with great facility to every interior part. [Illustration: _a_, A covered way and nest, on the branch of a tree, of the _Termites arborum_. _b_, Section of the Hill-nest of the _Termites bellicosi_, to show the interior. _c_, Hill-nest of the _Termites bellicosi_, entire.]