Subterraneity

SUBTERANEITY,^([sic]) a being ſubterraneous.

Source: wiktionary

The centralisation on which the empire is now firmly erected was the subterranean work which proceeded in the eighteenth century, though nothing appeared above ground but a feudal monarchy. The void in local administration and power which was left when the noblesse migrated to Paris and became a court plutocracy, was filled by the government employés, to whom alone the French peasant looked for any attempt at honest administration. They were the heralds of a centralised empire. The same subterraneity of advance is to be traced in the progress of thought. For instance, the Reformation and the overthrow of Scholasticism was a great and precise epoch, but the preparations for this bursting into life were being conducted while we were within the husk of scholasticism

Source: wiktionary

I am really less desiccated than I seem, however, for I am working with patient subterraneity at a trade which it is dishonour enough to practise, without talking about it: a trade supremely dangerous and heroically difficult—that credit at least belongs to it.

Source: wiktionary

The most persistent and distinctive of these features appear to be paired floor vaults, raised firebox, north antechamber, and four masonry roof supports, as well as more general characteristics such as size, a circular shape, a bench, and a determined effort to achieve subterraneity.

Source: wiktionary