An oblate flattened body, like a disk or plate, has c 2 -c 1 negative, so that the medium steers the body axially; this may be verified by a plate dropped in water, and a leaf or disk or rocket-stick or piece of paper falling in air.
The introduction of trunnionless guns recoiling axially through a fixed cradle enabled sights to be attached to the non-recoil parts of the mounting, so that the necessity of removing a delicate telescopic sight every round disappeared, and Q?'
These are cementite, a definite iron carbide, Fe 3 C, harder than glass and nearly as brittle, but probably very strong under gradually and axially applied stress; and ferrite, pure or nearly pure metallic a-iron, soft, weak, with high electric conductivity, and in general like copper except in colour.
Now rock the engine axially and pull it backward about 5/6 inches until the input shaft clears the clutch assembly then lower away.
The extension to a nucleus with an axially deformed ground state is straightforward.