The sun set, the twilight faded, some stars came out and still the flow went on. After a while it began to seem unnatural, uncanny. An hour and 20 minutes passed before a flashlight aimed into the hole showed that the supply was dwindling. It's probably the bat flight that has convinced so many people that undiscovered caverns and tunnels connect with the Devil's Sinkhole. It seems impossible for the one known room to hold them all.
But with its wings folded, a Mexican free-tailed bat, whose wingspread is 12 inches, is only about the size of your thumb. And the bats cling to each other in roosting, making a living blanket several inches deep, attached to the ceiling by the claws of the innermost layer. Because they weigh only a third of an ounce each, the bats can do this easily.
Some people find the sinkhole less than attractive. "A great festering sore in the skin of the earth," said a feature writer in the Houston Chronicle. The Department of the Interior rejected the sinkhole years ago as a possible national park, and Texas officials haven't wanted it for the state system, either.
It appeals primarily to scientists, to cavers and others who find beauty not only in scenery and sunsets but also in the workings of nature, her curious ways of doing things. Promoters have dreamed of subterranean boat rides, of big plastic tubes through which people could walk, looking out at an underwater underworld, floodlit and strange. The necessary passageways have not been discovered, and the guano remains a problem in attracting a large public devoted to deodorants and mouthwash. The Devil's Sinkhole remains basically unchanged. Its best exploiters so far are the bees, bats, swallows and owls.