Dr. Scheele now made a few experiments and quickly evolved a bomb that was as simple as it was efficient. It consisted merely of a section of lead pipe, about two and a half inches in diameter and three or four inches long. This cylinder was separated into two water-tight compartments by a thin disk of the sheet tin. In one of the two compartments was placed a chemical, and in the other a corrosive acid. The ends were then sealed and the bomb was complete. The acid slowly ate its way through the tin partition, and when at length a tiny hole was made, the acid and the chemical mingled and their action was to produce, without noise, a heat so intense that it melted the lead in the cylinder and the whole bomb flowed down into a molten mass so fervent that it would ignite any ordinary substance, such as coal or wood. No timing mechanism was necessary. The thickness of the tin partition determined the time at which the bomb would act. By careful experiment, Dr. Scheele was able to manufacture bombs that would become effective in two days, four days, six days, eight days--at will. For example, if the tin partition was made one sixtieth of an inch in thickness, the bomb would operate in forty-eight hours. The thickness necessary for the longer periods was established by actual test. As soon as the bomb was perfected, its manufacture was undertaken on a big scale. Soon the workroom aboard the _Friedrich der Grosse_ was turning out thirty-five of these “cigars,” as the Germans called them, every day. Altogether, before the game became too dangerous and Dr. Scheele was forced to flee, nearly five hundred bombs were manufactured. Next came the necessity for an organization to place these bombs upon the ships. First, the ships themselves must be known--their sailing dates, their names, their berths and cargoes. Through German sources of information, the data about merchant ships were gathered and by Dr. Carl Schimmel, another German agent in New York City, were listed and classified. These records were placed at the disposal of the bomb-placing squad.