I don't believe it has ever been used.

But if it was of good size it might prove handy for us at some time or another." They looked around, and finding some dry brushwood made two rude torches.

With these flaring brightly they entered the opening, the flooring of which was of rock and tolerably smooth.
"We could live in this cave, if it wasn't that the opening to it is in the gully," said Sam as they advanced.
"There may be another opening at the other end," said Tom.

"It is certainly quite long." They had advanced fully a hundred feet, and now found themselves in a chamber forty or fifty feet square.

The ceiling was arched and so high that they could not touch it without jumping up.
"This is as good as a house," said Tom.