"And money absolutely flung away. You have seen for yourself that there's no level s.p.a.ce hereabout for running off. And even supposing you could use the thing, it would be madness to do so. You'd be bound to come to grief; all flying men do sooner or later, and at the best you might find yourself landed thirty or forty miles away, with nothing but peaks and precipices between you and home. There are no repairing shops to fall back upon; no garages 'open day and night,' or anything of that sort. In short----"

"Don't rub it in, Uncle," said Lawrence. "The thing's here now, and we've got to make the best of it. Come on, Bob; let's go and look after the unloading; those fellows are sure to smash something."

The mules were led across the drawbridge to the west side of the gorge, and the separate parts of the machine were stacked near the dwelling house until a new shed could be constructed.

"What on earth we're to do with the petrol I don't know," said Mr.

Appleton. "We daren't have it within reach of the native workmen.

They're as careless as they are inquisitive, and we don't want a flare up."

"Isn't there room for the cans in the dynamite shed?" asked Lawrence.

The explosive was kept in a specially devised cache. The s.p.a.ce between the house and the cliff was boarded in. A doorway led from the house into this s.p.a.ce, which was divided by a part.i.tion, in which another door opened into a kind of strong room excavated in the hill side. There was room for the cans beside the boxes of dynamite.

"I shan't sleep at night now that we've got two explosives at our doors," said Mr. Appleton.

"Why didn't you store the stuff farther from the house?" asked Bob.

"Well, as a matter of fact wherever it was stored in the neighbourhood of the mine the result would be pretty much the same if it exploded. The best chance of safety was to have it under lock and key where n.o.body could get at it but myself. In for a penny, in for a pound. Trundle your cans through: if I'm not a false prophet they'll stay there until doomsday untouched."

When the boys entered the dark chamber between the house and the cliff, following Mr. Appleton, who carried an electric lamp, Bob uttered a sudden exclamation.

"I say, hanged if there isn't a machine gun!"

He pointed to a corner of the room, where the muzzle of the gun protruded from a nest of boxes.

"A very neat little machine," said Mr. Appleton. "I got it as a precaution against a second raid, and the difficulty of smuggling it through turned my surviving hairs grey. It came in parts among some engine fittings; the invoices are very interesting! A clear case of gun running, of course; but there was no other way; the government would never have allowed it to pa.s.s complete. n.o.body here knows of it but you; I put it together myself; and if you know anything about such things, Bob, I'll be glad if you'll overhaul it one of these days, and see if my amateurish efforts have been successful. Some of those boxes contain ammunition: smuggled in as dynamite. Now stack your cans, and when you've finished bring me the key. I'll have duplicates cut for you."

Later in the day the boys had a consultation.

"It's no good putting the aeroplane together until we've found a starting-place," said Lawrence.

"I know. I've looked all about, and can't find one. It's pretty rotten, and the old man is so ratty about it that I almost wish we'd never brought the thing."

"Oh, he'll come round. I bet you what you like that he'll be as keen as mustard if we can only get the thing going. We'll go out exploring; we're sure to hit on some place by and by."

They spent the spare time of two or three days in ranging up and down stream in search of a suitable starting-place. Every morning at breakfast Mr. Appleton dropped some quizzing remark that sorely tried Bob's temper. "How's the white elephant?" he would say; or "When is the ascent to take place?" Meanwhile the dismembered aeroplane lay under tarpaulin at the side of the house, and the Babu irritated Bob by kind enquiries.

"Will tender plant suffer, sir?" he asked one morning, when a sprinkling of snow lay upon the ground.

"What do you mean?" said Bob.

"Packages were marked 'fragile with care,' sir, and having been myself once fragile, delicate infant, sir, I have fellow feeling, that makes me wondrous kind."

"Well, be kind enough to shut up," said Bob.

At length, after much searching, they discovered a spot which, so far as s.p.a.ce was concerned, promised the solution of their difficulty. About a hundred yards up stream, at a somewhat higher level than the ledge upon which the mine buildings were situated, there was a similar ledge of about the same extent and on the same side of the gorge. But it was very difficult of access. It could not be approached from the mine, owing to the sheer wall of cliff that separated the two ledges. Nor could it be gained by bridging the river, for not only was the stream at this point much broader than lower down, but there was no rock in mid-channel that would serve as support. After a good deal of cogitation, Bob hit upon a plan which he determined to attempt.

On the way up, their caravan had crossed a stream by means of a bridge constructed on the cantilever principle, as is common in that country.

It occurred to Bob that there was a possibility of constructing a walk along the face of the cliff on the same principle.

"It will be a series of bridges made of overlapping planks," he said to Lawrence when explaining his idea. "There's plenty of timber in the shed."

"Which Uncle won't allow to be used."

"I'll talk him over."

"But I don't see how you're going to manage it. There are no supports."

"They are easily managed. All we've got to do to is drive beams into the rock, say twenty feet apart."

"Exactly; but how are you going to make holes in the rock? There's nothing to stand on, and we can't rig up scaffolding from the bottom of the river."

"I think we can do it all the same. What we have to do is to go to the extreme edge of the ledge of the silver mine, bore a couple of holes in the rock level with our heads, and drive in poles strong enough to support a swinging platform. You've seen house painters use them on house fronts at home. We can extend that with some planks, and so reach a position where similar holes can be bored a little farther away, and so on until we reach the farther ledge. A couple of stout miners on the platform can easily bore the holes, level with it, that we require for the larger beams, and when they are placed it will be a comparatively simple matter to lay planks upon them, and carry our cantilever walk the whole way. We can use the upper poles too: connect them by a rope, which we can cling to as we push the parts of the machine along on trolleys."

"It will take a very long time," said Lawrence dubiously.

"Not so long as you think if we can only persuade the old man to let us have a couple of men to work at it continuously. I'll tackle him to-night after supper when he's comfortably settled with a cigar."

Mr. Appleton happened to be in a very amiable mood when Bob broached the subject, and though he uttered doleful warnings and foretold broken limbs, and declared that he washed his hands of all responsibility, he told the boys that they might do as they pleased. Next day they invited volunteers from among the Kalmuck miners, and were somewhat surprised when Nurla Bai was the first to offer his services, explaining that he was an expert in carpentry. Taking this as a sign of grace, Bob engaged the man, and told him to choose his own a.s.sistant. Nurla at once suggested a dwarfish man named Tchigin, a thick-set, muscular fellow with a huge head covered with jet-black hair. Mr. Appleton called him Black Jack. They began work, and Bob was well pleased with their industry and skill. Before night there was a row of half-a-dozen of the smaller poles in position, and all was ready for the drilling of the larger hole for the first of the stout beams that were to support the wooden path.

On the subsequent days, with the number of workers increased to six, the work was carried on even more rapidly. The greatest difficulty encountered was a bend in the cliff a few yards before it opened out on to the ledge on which the aeroplane was to be put together. It cost a good deal of labour to shape the planks to the curve, and to fix the beams; and the boys regarded it as a further disadvantage that the ledge would be out of sight from the mine. Not that they could suppose that the aeroplane, when set up in its hangar there, would be in any danger of molestation, for the only approach was from the Pathan compound, and Mr. Appleton thought that the Pathans might be trusted. But they would have preferred that their flying machine should always be in sight.

However, there came a time when they were very thankful for the projecting corner of the cliff which had given them so much extra toil.

Their proceedings naturally caused a good deal of curiosity and excitement among the miners and the domestic staff. No one was more deeply interested than Ditta Lal, who numbered among his many accomplishments a smattering of theoretical engineering picked up in the course of his studies at Calcutta University. He talked very learnedly of strains and stresses, and often laid before the boys sc.r.a.ps of paper on which he had worked out magnificent calculations and drawn elaborate diagrams for their guidance. This amused them at first, but it became rather exasperating as the work progressed. He had a formula for everything; taught them exactly, to the fraction of an inch, how far the timbers should project from the ends of those supporting them, and what strain each portion of the structure could bear. As the successive bridges were completed, he proved, as he supposed, the accuracy of his calculations by venturing his own portly person upon them, at first with some timidity, but with more and more confidence as time went on. Mr.

Appleton, on the other hand, watched the work from the security of the compound until it pa.s.sed from sight round the shoulder of the cliff.

"You're a heap braver than I am," he said once to Ditta Lal. "I wouldn't trust myself on the thing for a pension, and you're heavier by three or four stone."

"Ah, sir, conscience makes cowards of us all," replied the Babu; "by which I understand immortal bard to mean, ignorance makes you funky.

With my knowledge of science, imbibed from fostering breast of Alma Mater, Calcutta University--of which, as you are aware, I have honour to be B.A.--I know to a T exact weight planks will support, all worked out by stunning formulae, sir. Knowledge is power, sir."

"Well, if you quote proverbs at me, I'll give you one: 'A little knowledge is a dangerous thing.'"

"A thousand pardons, sir, and with due respect, you have made a bloomer: misquotation, sir. Divine bard wrote: 'A little _learning_ is a dangerous thing;' and I understand him to mean, if even a _little_ learning in a man is dangerous to critic who tries to bowl him out, how much more dangerous is a fat lot!"

Mr. Appleton found it necessary at this point to break away, and Ditta Lal's further exposition was lost.

One evening, when the work of the bridge makers was nearing completion, the accepted explanation of Pope's line was brought home to the Babu by a rather unpleasant experience. He had walked along the finished portion of the pathway, which consisted of two lines of stout and broad planks supported by the cantilevers, these resting on the thick beams firmly embedded in the rock. The workmen on their swinging platform, Nurla Bai and Black Jack, had just laid the planks forming one bridge section across the gap, and were about to knock off work for the day. Ditta Lal was so eager to prove the soundness of his calculations, and demonstrate the valuable share he believed himself to have had in this engineering feat, that he took it into his head to walk across the planks to the other side. He had sufficient caution to hold on to the rope which had been carried along the smaller poles just above the level of his head.

"Hi, Ditta Lal! Come back!" shouted Bob from behind him. "The planks aren't nailed down yet."

The Babu halted and looked round with an air of pained astonishment.

"Sir," he said, "it is as safe as eggs. Planks are held firm by my own avoirdupois. I have worked it out."

Still holding the rope with one hand, with the other he drew from his pocket a sheet of paper on which he had made his last calculation.

"The weight which these planks will tolerate," he continued, "is eleven hundred and eighty-six pounds fifteen point eight ounces gross. My weight is two hundred and forty-four pounds and a fraction nett, by which I mean my own corpus without togs. Q.E.D. Suppose I jump, even then energy I develop is innocuous. I demonstrate the quod."