“You’ll be sorry, some day, you did that, Tom Swift! You’ll be sorry!”

“I’m sorry now that I didn’t kick you twice!” cried the angry inventor.

CHAPTER VII
STRUCK DOWN

“What’s the idea, Tom?” asked Ned when his chum had returned to the middle of the big, barnlike room where he stood in front of the Air Monarch, contemplating the powerful machine. “What’s the game?”

“A dirty game!” snapped out Tom Swift. “This Red Arrow gang has been trying to sneak around and discover some of my secrets for a long time. This is another attempt. Hussy has been here before. But I don’t think he’ll come again,” added the young inventor grimly.

“Are they trying to do you out of this new contrivance?” asked Ned.

“I don’t know that they are specifically after this,” stated Tom. “They’ll steal any new invention they can. But from the fact that Hussy was in here I judge they must have heard something about the Air Monarch and they want to get an idea of how she’s made. I suspected they might try something like this, and so I set several traps. Hussy happened to step into one,” and taking Ned to the various windows Tom showed other devices to nab intruders.

Going over the machine and making an examination of the workshop in company with Ned, convinced Tom that Hussy had been caught before he could do any damage.

“But from now on I’ll have to be doubly careful,” Tom declared. “And if I see Hussy around here again——” he did not finish, but it could easily be guessed what would happen.

From then on it became increasingly difficult for strangers to get near the Swift plant. Eradicate and Koku were kept on guard in the shop where the Air Monarch was housed and Mr. Swift, with a smile, said they at times even looked on him with suspicion.