To reach the most distant well, we go down yet one more ladder, the seventh. On one side of it there is a perpendicular wall, on the other a yawning gulf, so when one of the steps, merely round sticks tied with withes, gave way beneath our feet, we tightly grasped the stick above. Having reached the bottom of the ladder, we crawl on our hands and feet through a broken, winding passage about 800 feet long, then see before us a basin of crystalline water, and how thirsty we are! This basin is 1,400 feet from the mouth of the cave, and about 450 feet below the earth's surface. Several hundred people during five months in every year depend entirely on that source for all the water they use. With their frail pitchers and flaring torches they wend their way, gasping for breath, through the intricate passages, and reaching the water, are so profusely perspiring that they must wait before quenching their thirst. The way back is even harder, and they are tired and loaded; yet these people are such lovers of cleanliness that on their arrival at their poor huts, before tasting food, they will use some of the water that has cost them so much, to bathe their smoke-begrimed skin. As several women once fainted in the cave, men generally fetch the water now. Yucatan is, and has been for ages past, quite free from earthquakes, while all surrounding countries are from time to time convulsed. This immunity may be due to the vast caverns and numerous great wells existing throughout the land. Pliny the Elder was of opinion that if numerous deep wells were made in the earth to serve as outlets for the gases that disturb its upper strata, the strength of the earthquakes would be diminished, and if we may judge by Yucatan, Pliny was right in his conjectures. After him, other scientists who have carefully studied the subject have expressed the same opinion with regard to the efficacy of large wells. ALICE D. LE PLONGEON. Brooklyn, July 15, 1885. * * * * * Cholera failed to strike a single one of the 4,000 women employed in the national tobacco factory at Valencia, Spain, though the disease raged violently in that city, and the _Medical World_ recalls that tobacco workers were also noticed to enjoy exemption from attack during an epidemic at Amsterdam. * * * * * THE CABBAGE BUTTERFLY.