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 scraps 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 passed 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 formulæ, sir. Knowledge is power, sir." "Well, if you quote proverbs at me, I’ll give you one: ’A little knowledge is a dangerous thing.’"