"it is nothing very formidable," he said, taking a long cigar-shaped roll from his pocket. "it is an ordinary plumber’s smoke-rocket, fitted with a cap at either end to make it self-lighting. your task is confined to that. when you raise your cry of fire, it will be taken up by quite a number of people. you may then walk to the end of the street, and i will rejoin you in ten minutes. i hope that i have made myself clear?"