So side by side they advanced to the house.  Already a door had opened, showing Farmer Lovejoy with a lamp in his hand.  Evidently they had been anxiously waiting for the coming of the good doctor, and were possibly beginning to worry because he had failed as yet to show up with the medicine he had promised.

“It’s you, Frank, is it?” asked the farmer, as the lad drew near the stoop.

“Yes, sir,” replied the boy, cheerily.  “His machine broke down and I had to come on my wheel.  But father said it was very important that you have this medicine tonight.  He expects great things of it by morning.”

“Well,” said Farmer Lovejoy, warmly, “that was right nice of you to come all this way on your wheel, Frank.  But I guess it’s on’y what we’d expect from Doc Bird’s boy.  I saw ye make that trip up to the top of the mountain in your airship, Frank.  I tell ye it was wuth seein’!  Won’t you come in?  The missus’d like to see ye.”

“Why, yes, I will; because dad asked me to explain something to you and also get some information about Sue.  A few minutes will make little difference,” Frank said.

But, although he did not suspect it just then, even seconds came very near being of the greatest importance.

Perhaps he spent all of ten minutes in the Lovejoy home and in that time learned what his father wished to know.  The old farmer came to the door with him, shaking hands warmly.

“Once again I say I’m obliged to ye, Frank,” he remarked, with feeling, “for comin’ away out here to fetch the medicine.  It may be the means of savin’ our gal to us, who knows?  But I’ve got faith in your father.  If anybody kin fetch our Sue around he will.  Good night, lad.  Kaiser, mind your manners.  This is one of the best friends we’ve got.”

“Oh, that’s all right, sir,” declared Frank, quickly, as he patted the shaggy head of the big mastiff.  “We understand each other, don’t we, old boy?  He knew my voice, because a dog never forgets a friend, and I’ve played with him many the time.  Good night, Mr. Lovejoy.  Keep up your spirits.  Dad says Sue is going to get over this all right in a little time.”

Once again on the road he turned his face toward home.  After all, this six or seven-mile run was only a good touch of exercise, and he would sleep all the sounder on account of it.  Besides, Frank loved nothing better than to do something for the parent who all his life had been so indulgent to him.

As he pedaled along, keeping his eyes well ahead, so as to glimpse any vehicle that might loom up in his path, he was thinking of what Andy had in mind.  While the project was as yet rather uncertain, Frank seemed to feel that his cousin could never be wholly satisfied that he had done his duty by his father until he had spent some time down on the Isthmus trying to get some traces of the lost aeronaut.

“I reckon I ought to know something of Andy’s persistence,” he said to himself, with a chuckle.  “And now that he’s got this bee in his bonnet there’ll be no peace until he tries the scheme out.  Sure I’m with him from the word go.  It makes me shiver all over with expectation just to think of what glorious times we two chums might have—­hello! there’s something ahead, and I’d better slow up!”