The climbing soon became difficult, until at length we were going up hand over hand, taking advantage of crevices and knobs which an inexperienced eye would have regarded as incapable of affording a grip for the fingers or a support for the toes. Presently we arrived at the foot of a stupendous precipice, which was absolutely insurmountable by any ordinary method of ascent. Parts of it overhung, and everywhere the face of the rock was too free from irregularities to afford any footing, except to a fly. "Now, to borrow the expression of old Bunyan, we are hard put to it," I remarked. "If you will go to the left I will take the right and see if there is any chance of getting up." "I don't believe we could find any place easier than this," Hall replied, "and so up we go where we are." "Have you a pair of wings concealed about you?" I asked, laughing at his folly. "Well, something nearly as good," he responded, unstrapping his knapsack. He produced a silken bag, which he unfolded on the rock. "A balloon!" I exclaimed. "But how are you going to inflate it?" For reply Hall showed me a receptacle which, he said, contained liquid hydrogen, and which was furnished with a device for retarding the volatilization of the liquid so that it could be carried with little loss. "You remember I have a small laboratory in the abandoned mine," he explained, "where we used to manufacture liquid air for blasting. This balloon I made for our present purpose. It will just suffice to carry up our rope, and a small but practically unbreakable grapple of hardened gold. I calculate to send the grapple to the top of the precipice with the balloon, and when it has obtained a firm hold in the riven rock there we can ascend, sailor fashion. You see the rope has knots, and I know your muscles are as trustworthy in such work as my own." There was a slight breeze from the eastward, and the current of air slanting up the face of the peak assisted the balloon in mounting with its burden, and favored us by promptly swinging the little airship, with the grapple swaying beneath it, over the brow of the cliff into the atmospheric eddy above. As soon as we saw that the grapple was well over the edge we pulled upon the rope. The balloon instantly shot into view with the anchor dancing, but, under the influence of the wind, quickly returned to its former position behind the projecting brink. The grapple had failed to take hold. "'Try, try again' must be our motto now," muttered Hall. We tried several times with the same result, although each time we slightly shifted our position. At last the grapple caught. "Now, all together!" cried my companion, and simultaneously we threw our weight upon the slender rope. The anchor apparently did not give an inch. "Let me go first," said Hall, pushing me aside as I caught the first knot above my head. "It's my device, and it's only fair that I should have the first try."