He started off early one morning, in the swift little craft Butterfly, and soon had reached Chester.  The diamond brooch was ready for him.

“It is one of the most beautiful stones we have ever set,” the diamond merchant told him.  “Don’t forget, if you find any more, Mr. Swift, to let us have a chance to bid on them.”

“I may,” Tom promised, rather indefinitely.  Then, having purchased his electrical supplies, he made a quick trip to Shopton, stopping on the way to call on Miss Nestor.

“Why Tom, I’m delighted to see you!” cried the girl, blushing prettily.  “Did you come for some apple turnovers?” and she laughed, as she referred to a call Tom had once paid, when a new cook had been engaged, and when the pastry formed a feature of the meal.

“No turnovers this time,” said the young inventor.  “I came to wish you many happy returns of the day.”

“Oh, you remembered my birthday!  How nice of you!”

“And here is something else,” added our hero, rather awkwardly, as he handed her the diamond pin.

“Oh, Tom!  This for me!  Oh, it’s too lovely—­it’s far too much!”

“It isn’t half enough!” he declared, warmly.  “Oh, what a large diamond!” Mary cried as she saw the sparkling stone.  “I never saw one so large and beautiful!”

“It’s just as easy to make them large as small,” explained Tom.

“Make them?” she looked the surprise she felt.

“Yes, I’m about to start for the place where diamonds are made.”

“Oh, Tom!  But isn’t it dangerous?  I mean won’t you have to go to some far country—­like Africa—­to get to where diamonds are made?”

“Well, we are going on quite a trip, but not as far as that.  And as for the danger—­well, we’ll have to take what comes,” and he told her something of the proposed quest.

“Oh, it sounds—­sounds scary!” Mary exclaimed, when she had heard of Mr. Jenks’ experience.  Do be careful, Tom!”

“I will,” he promised, and, somehow he was glad that she had cautioned him thus—­and in such tones as she had used.  For Mary Nestor was a girl that any young chap would have been glad to have manifest an interest in him.

“Well, I guess I’ll have to say good-by,” spoke Tom, at length.  “We expect to start in a couple of days, and I may not get another chance to see you.”

“Oh, I—­I hope you come back safely,” faltered Mary, and then she held out her hand, and Tom—­well, it’s none of our affair what Tom did after that, except to say that he hurried out, fairly jumped into his monoplane, and completed the trip home.

As the Red Cloud has been fully described in the volume entitled “Tom Swift and His Airship,” we will not go into details about it now.  Sufficient to say that it was a combination of a biplane and dirigible balloon.  It could be used either as one or the other, and the gas-bag feature was of value when the wind was too great to allow the use of the planes, or when the motive power, for some reason stopped.  In that event the airship could remain suspended far above the clouds if necessary.  There was provision for manufacturing the gas on board.