This coal-scuttle was the thing which might help him! Above the area door was a small window which was supposed to light the entry. He could not reach it, and, if he reached it, he could not open it. He could throw pieces of coal at the glass and break it, and then he could shout for help when people passed by. They might not notice or understand where the shouts came from at first, but, if he kept them up, some one's attention would be attracted in the end. He picked a large-sized solid piece of coal out of the heap in the scuttle, and threw it with all his force against the grimy glass. It smashed through and left a big hole. He threw another, and the entire pane was splintered and fell outside into the area. Then he saw it was broad daylight, and guessed that he had been shut up a good many hours. There was plenty of coal in the scuttle, and he had a strong arm and a good aim. He smashed pane after pane, until only the framework remained. When he shouted, there would be nothing between his voice and the street. No one could see him, but if he could do something which would make people slacken their pace to listen, then he could call out that he was in the basement of the house with the broken window. "Hallo!" he shouted. "Hallo! Hallo! Hallo! Hallo!" But vehicles were passing in the street, and the passers-by were absorbed in their own business. If they heard a sound, they did not stop to inquire into it. "Hallo! Hallo! I am locked in!" yelled Marco, at the topmost power of his lungs. "Hallo! Hallo!" After half an hour's shouting, he began to think that he was wasting his strength. "They only think it is a boy shouting," he said. "Some one will notice in time. At night, when the streets are quiet, I might make a policeman hear. But my father does not know where I am. He will be trying to find me--so will Lazarus--so will The Rat. One of them might pass through this very street, as I did. What can I do!" A new idea flashed light upon him. "I will begin to sing a Samavian song, and I will sing it very loud. People nearly always stop a moment to listen to music and find out where it comes from. And if any of my own people came near, they would stop at once--and now and then I will shout for help." Once when they had stopped to rest on Hampstead Heath, he had sung a valiant Samavian song for The Rat. The Rat had wanted to hear how he would sing when they went on their secret journey. He wanted him to sing for the Squad some day, to make the thing seem real. The Rat had been greatly excited, and had begged for the song often. It was a stirring martial thing with a sort of trumpet call of a chorus. Thousands of Samavians had sung it together on their way to the battle-field, hundreds of years ago.