They looked at one another and laughed. All three of them were blackened and grimed and greasy, smothered from head to foot in fatty soot flakes. Three more disreputable looking ruffians it would have been hard to imagine. There was something grotesque in the reflection that every Londoner was the same. It was light now, broad daylight, with a round globe of sun climbing up out of the pearly mists in the East. They revelled in the brightness and the light. Below them lay the thick layers of fog that would be a shroud in earnest if nothing came to dispel it. "We're a thousand feet above the city," Eldred said presently. "We had better pay out five hundred feet of cable." To a hook at the end of a flexible wire Hackness attached a large bomb filled with a certain high explosive. Through the eye of the hook another wire--an electric one--was attached. The whole thing was carefully lowered to the full extent of the cable. Two anxious faces peered from the car. Grimfern appeared to be playing carelessly with a polished switch spliced into the wire. But his hands were shaking. Eldred nodded. He had no words to spare just then. Grimfern's forefinger pressed the polished button, there was a snap and almost immediately a roar and a rush of air that set the aerophane rocking violently. All about them the clouds were spinning, below the foggy envelope was twisted and torn as smoke is blown away from a huge stack by a high wind. "Look," Hackness yelled. "Look at that!" [Illustration: The brilliant light of day shone through down into London as from a gigantic skylight.] He pointed downwards. The force of the explosion had literally torn a hole in the dense foggy curtain. The brilliant light of day shone through down into London as from a gigantic skylight. This is what the amazed inhabitants of central London saw as they rushed out of their houses after what they imagined to be a shock of earthquake. The effect was weird, wonderful, one never to be forgotten. From a radius of half a mile from St. Paul's, London was flooded with brilliant light. People rubbed their eyes, unable to face the sudden and blinding glare. They gasped and thrilled with exultation as a column of fresh sweet air rushed to fill the vacuum. As yet they knew nothing of the cause. That brilliant shaft of light showed strange things. Every pavement was black as ink, the fronts of the houses looked as if they had been daubed over with pitch. The roads were dark with fatty soot. On Ludgate Hill were dozens of vehicles from which the horses had been detached. There were numerous motor cars apparently lacking owners. A pickpocket sat in the gutter with a pile of costly trinkets about him, gems that glittered in the mud. These things had been collected before the fog grew beyond endurance. Now they were about as useful to the thief as an elephant might have been.