“Koku!” suddenly called Tom.

The giant stepped into the front office.  He had been standing near the door, inside the main shop.  Mr. Turbot who had stretched forth his hand, as though to seize Tom, and his companion, who had advanced toward Ned, fairly jumped back in fright at the sight of the big man.

“Koku,” went on Tom, in even tones, “just show these gentlemen to the front door—­and lock it after them,” he added significantly, as he turned back into the shop, followed by Ned.

“Yes, Mr. Tom,” answered the giant, and then, with his big hand, and brawny fist, he gently turned the two men toward the outer door.  They were gasping in surprise as they looked at the giant.

“You’ll be sorry for this, Tom Swift!” exclaimed Mr. Turbot.  “You’ll regret not having taken our offer.  This Period chat is only a small dealer.  We can do better by you.  You’ll regret—­”

“You’ll regret coming here again,” snapped Tom, as he closed the door of his shop, leaving Koku to escort the baffled plotters to their auto.  Shortly afterward Tom and Ned heard the car puffing away.

“Well, they came, just as Mr. Period said they would,” spoke Tom, slowly.

“Yes, and they went away again!” exclaimed Ned with a laugh.  “They had their trip for nothing.  Say, did you see how they stared at Koku?”

“Yes, he’s a helper worth having, in cases like these.”

Tom wrote a full account of what had happened and sent it to Mr. Period.  He received in reply a few words, thanking him for his loyalty, and again warning him to be on his guard.

In the meanwhile, work went on rapidly on the Wizard Camera.  Briefly described it was a small square box, with a lens projecting from it.  Inside, however, was complicated machinery, much too complicated for me to describe.  Tom Swift had put in his best work on this wonderful machine.  As I have said, it could be worked by a storage battery, by ordinary electric current from a dynamo, or by hand.  On top was a new kind of electric light.  This was small and compact, but it threw out powerful beams.  With the automatic arrangement set, and the light turned on, the camera could be left at a certain place after dark, and whatever went on in front of it would be reproduced on the moving roll of film inside.

In the morning the film could be taken out, developed, and the pictures thrown on a screen in the usual way, familiar to all who have been in a moving picture theatre.  With the reproducing machines Tom had nothing to do, as they were already perfected.  His task had been to make the new-style camera, and it was nearly completed.

A number of rolls of films could be packed into the camera, and they could be taken out, or inserted, in daylight.  Of course after one film had been made, showing any particular scene any number of films could be made from this “master” one.  Just as is done with the ordinary moving picture camera.  Tom had an attachment to show when one roll was used, and when another needed inserting.