The quantity of nitrous earth contained in the Cave is "sufficient to supply the whole population of the globe with saltpetre." "The dirt gives from three to five pounds of nitrate of lime to the bushel, requiring a large proportion of fixed alkali to produce the required crystalization, and when left in the Cave become re-impregnated in three years. When saltpetre bore a high price, immense quantities were manufactured at the Mammoth Cave, but the return of peace brought the saltpetre from the East Indies in competition with the American, and drove that of the produce of our country entirely from the market. An idea may be formed of the extent of the manufacture of saltpetre at this Cave, from the fact that the contract for the supply of the fixed alkali alone for the Cave, for the year 1814, was twenty thousand dollars." "The price of the article was so high, and the profits of the manufacturer so great, as to set half the western world gadding after nitre caves--the gold mines of the day. Cave hunting in fact became a kind of mania, beginning with speculators, and ending with hair brained young men, who dared for the love of adventure the risk which others ran for profit." Every hole, remarked an old miner, the size of a man's body, has been penetrated for miles around the Mammoth Cave, but although we found "_petre earth_," we never could find a cave worth having. CHAPTER II. Gothic Gallery--Gothic Avenue--Good Road--Mummies--Interesting Account of Them--Gothic Avenue once called Haunted Chamber--Why so Named-- Adventure of a Miner in Former Days. In looking from the ruins of the nitre works, to the left and some thirty feet above, you will see a large cave, connected with which is a narrow gallery sweeping across the Main Cave and losing itself in a cave, which is seen above to your right This latter cave is the Gothic Avenue, which no doubt was at one time connected with the cave opposite and on the same level, forming a complete bridge over the main avenue, but afterwards broken down and separated by some great convulsion. The cave on the left, which is filled with sand, has been penetrated but a short distance; still from its great size at its entrance, it is more than probable, that, were all obstructions removed, it might be found to extend for miles. [Illustration: ENTRANCE TO THE GOTHIC AVENUE. On Stone by T. Campbell Bauer & Teschemacher's Lith.] While examining the old saltpetre works, the guide left us without our being aware of it, but casting our eyes around we perceived him standing some forty feet above, on the projection of a huge rock, or tower, which commands a view of the grand gallery to a great extent both up and down.