The effect was to make the beam of light much stronger and sharper, also to shift it on to the point or foot of the spinning mountain and, by an aiming of the lens from time to time, to keep it there.
This went on for a while, since the dreadful thing did not travel fast notwithstanding the frightful speed of its revolutions.

I should doubt indeed if it advanced more quickly than a man could walk; at any rate so it seemed to us.

But we had no means of judging its real rate of progress whereof we knew as little as we did of the course it followed in the bowels of the earth.

Perhaps that was spiral, from the world's deep heart upwards, and this was the highest point it reached.

Or perhaps it remained stationary, but still spinning, for scores or hundreds of years in some central powerhouse of its own, whence, in obedience to unknown laws, from time to time it made these terrific journeys.
No one knows, unless perhaps Oro did, in which case he kept the information to himself, and no one will ever know.