The Collaborative International Dictionary
Subterrene \Sub`ter*rene"\, a. [L. subterrenus, equiv. to subterraneus.] Subterraneous. [Obs.]
Wikipedia
A Subterrene (, ) is a vehicle that travels underground (through solid rock/soil) much as a submarine travels underwater, either by mechanical drilling, or by melting its way forward. Subterrenes existed first in fiction as mechanical drillers, with real-world thermal designs and examples following in the second half of the 20th century.
Fictional subterrenes are often depicted as cylindrical in shape with conical drill heads at one or both ends, sometimes with some kind of tank-tread for propulsion, and described either as leaving an empty tunnel behind it, or as filling the space behind it with mining debris. The plausibility of such machines has declined with the advent of the real-world tunnel boring machines, which demonstrate the reality of the boring task. Tunnel boring machine themselves are not usually considered to be subterrenes, possibly because they lack the secondary attributes - mobility and independence - that are normally applied to vehicles.
A real-world, mobile subterrene must work thermally, using very high temperature and immense pressure to melt and push through rock. The front of the machine is equipped with a stationary drill tip which is kept at . The molten rock is pushed around the edges as the vehicle is forced forward, and cools to a glass-like lining of the tunnel. Massive amounts of energy are required to heat the drill head, supplied via nuclear power or electricity. Patents issued in the 1970s indicate that U.S. scientists had planned to use nuclear power to liquefy lithium metal and circulate it to the front of the machine (drill). An onboard nuclear reactor can permit a truly independent subterrene, but cooling the reactor is a difficult problem. The Soviet Union is purported to have built such a "battle mole", which operated until its onboard reactor failed.
On line information presents research was funded by the United States Government for the Los Alamos Scientific Laboratories University of California, Los Alamos, New Mexico for a project Camelot under the heading Systems and Cost Analysis for a Nuclear Subterrene Tunneling Machine. A patent was subsequently issued under number 3,693,731 on September 26, 1972. A patent search can be made with full text and images at www.uspto.gov.
The design concepts fall into similar designs of current technology of our nuclear submarine fleet and existing tunnel boring technology as used in the Chunnel between England and France, but with the added feature of melting rock for the tunnel wall lining.
See Project Camelot link here: http://projectcamelot.org/la5354ms.pdf
Usage examples of "subterrene".
No ordinary man had brought red death upon this haunter of subterrene passageways.
Someone, a man wearing buskins or sandals, had paced this subterrene corridor since Cormac and Samaire had, nor had it been one of the slain Britons.
Cormac mac Art emerged from the subterrene escape-route from the Castle of Atlantis, and he drew in great lungsful of clear clean air, which he released in long suspirations.
Pacing determinedly back along the subterrene passage from sea to castle, he wondered at those inexplicable sounds well ahead, with no idea as to what they might be.
How did I know that the long subterrene passage to the Square of Pillars ought to lie on the left one level above me?
Since this was a subterrene house - connecting highway, there were no archways save when the route led through the lower levels of various buildings.
And I thought of the tales of the modern blackfellows, wherein the horror of great winds and nameless subterrene ruins was dwelt upon.
I did not bring back the metal case that would have been a proof, and so far those subterrene corridors have not been found.
This bore regular fruit, for after the first interview the manuscript records daily calls of the young man, during which he related startling fragments of nocturnal imaginery whose burden was always some terrible Cyclopean vista of dark and dripping stone, with a subterrene voice or intelligence shouting monotonously in enigmatical sense-impacts uninscribable save as gibberish.
Since this was a subterrene house --connecting highway, there were no archways save when the route led through the lower levels of various buildings.
Then we saw a series of cartouches--the continuous band arrangement being frequently interrupted in these late carvings--depicting a constantly growing migration to the nearest refuges of greater warmth--some fleeing to cities under the sea off the far-away coast, and some clambering down through networks of limestone caverns in the hollow hills to the neighboring black abyss of subterrene waters.
During the heavy spring rains of 1769 the two watchers kept a sharp eye on the steep river-bank to see if any subterrene secrets might be washed to light, and were rewarded by the sight of a profusion of both human and animal bones in places where deep gullies had been worn in the banks.
Both were plainer and more hideous in the great pillared hall than anywhere else, and carried a vague impression of being far below, even in this dark nether world of subterrene mystery.
Great gardens and columned streets led from the cliffs and from each of the six sphinx-crowned gates to a vast central plaza, and in that plaza was a pair of winged colossal lions guarding the top of a subterrene staircase.
He did not like to think of going again to the subterrene world of Gugs and risking once more that hellish tower of Koth with its Cyclopean steps leading to the enchanted wood, yet he felt he might have to try this course if all else failed.