what that something is. Have you decided how a bomb was exploded on top of this roof in broad daylight, with people watching the house? Until you've got that, you are nowhere."
"It might have been thrown from the top of a building up there."
"And anybody could have seen it. No. There was only one possible way, besides electric wiring, and here it is." He opened his hand and disclosed a small twisted bullet.
"Oh!" cried the girl. "They put the bomb there and then shot at it."
"Yes. Shot at it and missed the first time. Now, here we find the place where the first bullet, going wild, hit this piece of scantling. This makes it merely a matter of surveying. If you will stand with the back of your head where the indentation of this bullet is, then sight across the approximate middle of the hole in the roof caused by the explosion, you will probably get some idea of where the bullet came from. What do you see?"
"Well, it might have been aimed from any one of those three windows over there, in the building next to the shirt factory. I should say it came from the second one, where the potted plant is."
"One of them, certainly," answered Astro. "But we shall have to investigate them all, if we are to be conscientious about it, and for that purpose I suggest we look up McGraw again."
As they went down-stairs, Valeska asked, "When did the first explosion occur?"
"At night."
