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.”

In a minute he was many feet up the wall, climbing swiftly hand over hand, but occasionally stopping and twisting his leg around the rope while he took breath.

“It’s easier than I expected,” he called down, when he had ascended about one hundred feet. “Here and there the rock offers a little hold for the knees.”

I watched him, breathless with anxiety, and, as he got higher, my imagination pictured the little gold grapple, invisible above the brow of the precipice, with perhaps a single thin prong wedged into a crevice, and slowly ploughing its way towards the edge with each impulse of the climber, until but another pull was needed to set it flying! So vivid was my fancy that I tried to banish it by noticing that a certain knot in the rope remained just at the level of my eyes, where it had been from the start. Hall was now fully two hundred feet above the ledge on which I stood, and was rapidly nearing the top of the precipice. In a minute more he would be safe.

Suddenly he shouted, and, glancing up with a leap of the heart, I saw that he was falling! He kept his face to the rock, and came down feet foremost. It would be useless to attempt any description of my feelings; I would not go through that experience again for the price of a battleship. Yet it lasted less than a second. He had dropped not more than ten feet when the fall was arrested.

“All right!” he called, cheerily. “No harm done! It was only a slip.”

But what a slip! If the balloon had not carried the anchor several yards back from the edge it would have had no opportunity to catch another hold as it shot forward. And how could we know that the second hold would prove more secure than the first? Hall did not hesitate, however, for one instant. Up he went again. But, in fact, his best chance was in going up, for he was within four yards of the top when the mishap occurred. With a sigh of relief I saw him at last throw his arm over the verge and then wriggle his body upon the ledge. A few seconds later he was lying on his stomach, with his face over the edge, looking down at me.

“Come on!” he shouted. “It’s all right.”

When I had pulled myself over the brink at his side I grasped his hand and pressed it without a word. We understood one another.

“It was pretty close to a miracle,” he remarked at last. “Look at this.”

The rock over which the grapple had slipped was deeply scored by the unyielding point of the metal, and exactly at the verge of the precipice the prong had wedged itself into a narrow crack, so firmly that we had to chip away the stone in order to release it. If it had slipped a single inch farther before taking hold it would have been all over with my friend.

Such experiences shake the strongest nerves, and we sat on the shelf we had attained for fully a quarter of an hour before we ventured to attack the next precipice which hung beetling directly above us. It was not as lofty as the one we had just ascended, but it impended to such a degree that we saw we should have to climb our rope while it swung free in the air!

Luckily we had little difficulty in getting a grip for the prongs, and we took every precaution to test the security of the anchorage, not only putting our combined weight repeatedly upon the rope, but flipping and jerking it with all our strength. The grapple resisted every effort to dislodge it, and finally I started up, insisting on my turn as leader.

The height I had to ascend did not exceed one hundred feet, but that is a very great distance to climb on a swinging rope, without a wall within reach to assist by its friction and occasional friendly projections. In a little while my movements, together with the effect of the slight wind, had imparted a most distressing oscillation to the rope. This sometimes carried me with a nerve-shaking bang against a prominent point of the precipice, where I would dislodge loose fragments that kept Hall dodging for his life, and then I would swing out, apparently beyond the brow of the cliff below, so that, as I involuntarily glanced downward, I seemed to be hanging in free space, while the steep mountain-side, looking ten times steeper than it really was, resembled the vertical wall of an absolutely bottomless abyss, as if I were suspended over the edge of the world.

I avoided thinking of what the grapple might be about, and in my haste to get through with the awful experience I worked myself fairly out of breath, so that, when at last I reached the rounded brow of the cliff, I had to stop............