were a little heavier I could make that answer, but I'm afraid it's much too light."

The idea of utilizing the knife in this way seemed, however, to haunt him, and at last he exclaimed:

"I don't see why the knife won't answer almost as well as my arm. Being so light, the reaction will, of course, be much less, and it will consequently take me a great deal longer to reach the side of the car.

"Let me see; the calculation is an easy one to make. My knife weighs about one ounce, and my body weighs over one hundred pounds. Consequently, if I throw the knife with sufficient force to make it reach one side of the car in a single second, the reaction will force my body to the other side of the car in sixteen hundred seconds, that is to say, about twenty-six minutes. In other words, I shall not be obliged to remain suspended here more than half an hour, at the most. That's bad enough, I must confess, but it might have been worse."

Just as William was about to throw the knife, a new thought stayed his hand. "I forgot the resistance of the air!" he exclaimed. "The knife will pass through the air all right, because it is