There was no pump on the premises but I did have some chemicals: the match heads. They were old style too, like a lot of things in Peru: the strike-once-and-throw-away kind. I sat on the floor and started to work, chipping the heads off the matchsticks, collecting the dry, purplish material on a scrap of paper. Thirty-eight matches gave me a respectable sample. I packed it together, rolled it in the paper, and crimped the ends. Then I tucked the makeshift firecracker into the hole the screw had come from. Using the metal scrap I scraped at the threads of the screw, blurring them. Then I started it in the hole, half a dozen turns, until it came up against the match-heads. The shoes Margareta had bought me had built-up leather heels: hell on the feet, but just the thing to pound with. * * * * * I took the shoe by the toe and hefted it: the flexible sole gave it a good action, like a well-made sap. There were still a couple of "if's" in the equation, but a healthy crack on the screw ought to drive it against the packed match-heads hard enough to detonate them, and the expanding gasses from the explosion ought to exert enough pressure against the glass panels to break them. I'd know in a second. I flattened myself against the wall, brought the shoe up, and laid it on the screw-head. There was a deafening boom, a blast of hot air, and a chemical stink, then a gust of cool night wind--and I was on the sill, my back to the street six hundred feet below, my fingers groping for a hold on the ledge above the window. I found a grip, pulled up, reached higher, got my feet on the muntin strip, paused to rest for three seconds, reached again.... I pulled my feet above the window level and heard shouts in the room below: "--fool killed himself!" "Get a light in here!" I clung, breathing deep, and murmured thanks to the architect who had stressed a strong horizontal element in his facade and arranged the strip windows in bays set twelve inches from the face of the structure. Now, if the boys below would keep their eyes on the street underneath long enough for me to get to the roof-- I looked up, to get an idea how far I'd have to go--and gripped the ledge convulsively as the whole building leaned out, tilting me back....