"'Lomas, when he went on duty that Saturday night, took the bit of tube charged with compressed hydrogen and an empty toy balloon with him. You will remember that that night was very dark, and that the wind had been blowing very steadily all day towards the Barkly Hills. Well, when everything was quiet he filled the balloon with gas, tied the diamond—'
"'But how did he get the diamond out of the safe? The Secretary saw it locked up that evening!' I exclaimed, my curiosity getting the better of my prudence.
"'It was not locked up in the safe at all that night,' he answered, smiling with a sort of ghastly satisfaction. 'Lomas and I, as you know, took the tray of diamonds to the safe, and, as far as the Secretary could see, put them in, but as he put the tray into its compartment he palmed the big diamond as I had taught him to do in a good many
