"That's right—take all the information you can get," was the smiling response.
"We will now assume that the bombs are in place in the holes in the floor of the cabin," Tom went on. "As I sit here I have before me three buttons. They control the magnets that hold the bombs in place. If I press one of the buttons it breaks the electrical current, the magnet no longer has any attraction, and it releases the explosive. Now look down. I am going to try and drop a chalk bomb near that stone fence."
The Mars was then flying over a large field and a stone fence was in plain view.
"Here she goes!" cried Tom, as he made some rapid calculations from his gauge instruments. There was a little click and the chalk bomb dropped. There was a plate glass floor in part of the cabin, and through this the progress of the pasteboard bomb could be observed.
"She'll never go anywhere near the fence!" declared Ned. "You let it drop too soon, Tom!"
"Did I? You just watch. I had to allow for the momentum that would be given the bomb by the forward motion of the balloon."
Hardly had Tom spoken than a puff of white was seen on the very top of the fence.
"There it goes?" cried the lieutenant. "You did the trick, Swift!"
"Yes, I thought I would. Well, that shows my gauges are correct, anyhow. Now we'll try the other two bombs."
In succession they were released from the bottom of the cabin, at other designated objects. The second one was near a tree. It struck within five feet, which was considered good.