Hope measured it.

Give up working downward, pick into the sides of that hall, for in that hall I see them at night; sometimes they are alive, sometimes they are dead, sometimes they are dying.

I shall go mad, I shall go mad!" With this he went raging about, giving the wildest orders, with the looks and tones of a madman.

In a minute he had a cage ready for Walter, and twenty fresh-lit lamps, and down went Walter with more men and pickaxes.
As soon as he got out of the cage he cried, wildly, "Stop that, men, and do as I do." He took a sweep with his pick, and delivered a horizontal blow at the clay on that side of the shaft Bartley had told him to attack.

His pickaxe stuck in it, and he extricated it with difficulty.
"Nay, master," cried a miner who had fallen in love with him, "drive thy pick at t' coal." Walter then observed that above the clay there was a narrow seam of coal; he heaved his pick again, but instead of striking it half downward, as he ought to have done, he delivered a tremendous horizontal blow that made the coal ring like a church bell, and jarred his own stout arms so terribly that the pick fell out of his numbed hand.
Then the man who had advised him saw that he was disabled for a time, and stepped into his place.
But in that short interval an incident occurred so strange and thrilling that the stout miners uttered treble cries, like women, and then one mighty "Hah!" burst like a diapason from their manly bosoms..