Meanwhile, all possible steps were taken to prepare for the possible arrival of the _Scorpion_. The Bristol machines, after being carefully stowed away in a gap between the trees, were so camouflaged by branches of pine and larch that they presented but a very indistinct object from the air, and, unless their presence were known, might easily remain unobserved. After some time had been spent in examining the highly developed and intricate mechanism of the devil’s workshop, as the place was now called, the Commissioner suddenly turned upon his chief mentor, and said:-- "By the way, Keane, have you discovered any drawings or designs of this wonderful aeroplane? I don’t see any amongst this pile of papers, and the professor does not seem inclined to help us at all." "No, sir. We have searched the place carefully, but we have found nothing. Part of the machine could certainly be reconstructed from those spares, but all the important parts are missing. I have an overwhelming curiosity to see the machine, though, and hope that I may not have this pleasure much longer delayed." "Then we have nothing but these photographs," returned the captain. "Photographs?" echoed Keane. "Yes. Why, I forgot to tell you in the bewilderment and excitement of the last hour, that Captain Watson here managed to secure three snapshots of the raider in mid-air, whilst his airship was being attacked." "It was the boy Gadget who secured them, sir," interposed the air-skipper, anxious to give credit where credit was due. "Oh, yes, Keane, I ought to say that it was a smart little beggar called Gadget, a stowaway, who really secured the photographs, and hid them away from the brigand. We must see that the little chap is properly rewarded when we return." "Let me see the pictures, sir," requested Keane, eager to get some idea of his future opponent. "Here they are. I have had them developed and enlarged. They should be extremely useful to us, as we shall shortly have to encounter this Sultan Selim, Air King of the Hamadian Desert, the world’s greatest bandit, who had the audacity to send me this document by the captain." And here the colonel, having retailed the whole story of the fight in the desert, showed the brigand’s letter, which had been brought to London the previous day by the fast aeroplane which had carried the skipper of the air-liner. Keane turned in amazement from the clear photographs of the phantom-bird to the brief, audacious letter of the phantom airman, and read as follows:-- "To Colonel Tempest, D.S.O., M.C., Commissioner of Aerial Police, Scotland Yard, London, W.C.