information proved of no help in solving the mystery, but rather deepened it.
After a thorough and careful examination of the burglar-alarm and all its attachments, annunciators and indicators, the electrical expert pronounced it the most marvellous affair of its kind he had ever seen. He said that it was in perfect order, and that, owing to its wonderful and ingenious mechanism, it was positively impossible that any one should have gone out of the house between 12.30 a.m., when it was turned on, and 7.30 a.m., when Driggs had turned it off. The man staked his entire reputation as an electrical expert on the positiveness of this statement; after which there was of course nothing to do but to theorize that Justin Arnold was still under his own roof, although this seemed equally impossible.
As to Doctor Gaspard, he simply pooh-poohed any suggestion that there was any flaw in Arnold's physical constitution or mental equipment. While, he said, a stroke of apoplexy or paralysis might happen to any one, yet some were far more liable to it than others, and Justin Arnold was the farthest possible removed from the type of constitution that would indicate that sort of thing. He, too, was willing to stake his professional reputation that whatever had happened to Arnold, if anything, was not a physical seizure of any kind. Nor was it any variety of mental derangement. Justin Arnold's brain was not of a sort to give way in an emergency, or under mental pressure of any kind; and, moreover, no emergency or mental pressure had transpired that would even hint at such a condition.
"He is one of the soundest-minded men I know," concluded Doctor Gaspard, "and while I agree with you all that it is most mysterious, yet I must suspect the fallibility of a perfect machine before I can admit a hypothesis implying sudden dementia on the part of Justin Arnold."
"And that's where it stands," said Fred Crane, thoughtfully; "either Arnold's strong, well-balanced brain gave way, or else his infallible burglar device did. Both these things are pronounced impossible by experts,—so what is there left to think?"
As the electrical expert was still present, he looked upon this speech as a direct implication that he had misunderstood or misrepresented the infallibility of the burglar-alarm. Being of a somewhat choleric nature, he chose to take offence at this and remarked heatedly that for his part he would sooner suspect the strongest mind in the strongest body in the world, than the fallibility of a perfect machine!
"And a perfect machine it is," he went on, earnestly. "You ladies and gentlemen who are unacquainted with the real working of such a marvellous piece of ingenuity, cannot expect to understand how wonderful and beautiful its various perfections are. But you may take my word for it, as an experienced electrician, there never has been anything finer made of its kind; and you may be convinced that it is a physical impossibility for Mr. Arnold to have left this house secretly while that alarm was on."
The old doctor sniffed, and the young electrician glared back at him. Mr. Crane strove to reconcile the irreconcilable, by saying: "Then we must conclude that since Arnold was sane and in his right mind, and since he could not get out of this house, that he must still be in the house, and that of his own knowledge and volition he is hiding himself from us. We have searched the house thoroughly; but I suppose there is a possibility of some secret passage or hiding place where he might be hidden, though I can conceive of no reason for such an act."
Old Doctor Gaspard rose stiffly. "I cannot acquaint you with Mr. Arnold's reasons for what seems to be an eccentric performance, but I can assure you that whatever Mr. Arnold is doing, he knows perfectly well why he is doing it. As I assume I cannot help you further in what must necessarily now become a search for the missing man, I will ask you to excuse me."
With a disdainful glance at the electrician, whom he considered his rival in the mere question of expert evidence, Doctor Gaspard made his adieux and went away.
The electrician, concluding that his usefulness was also at an end, followed, and the members of the household were again left to confront the ever deepening mystery of the disappearance of Justin Arnold.
Though appalled by the situation, Fred Crane was taking a lively interest in this opportunity to test his detective powers, and though he had as yet accomplished nothing positively, yet he had the negative evidence of the two experts who had been called in, to work upon.
"It's just this way," he said. "Arnold must be somewhere. He couldn't get out of the house, so he must be in the house. We've not been able to find him, so we are forced to the conclusion that there is some kind of a secret passage by which he has access to the outer world. This is not an unprecedented case. In many old houses like this there are secret and subterranean passages unsuspected by chance observers."
"But not in this country," remarked Mrs. Duncan. "I've never heard of such thing's over here."
"But there is no other explanation, Mrs. Duncan," went on Crane, earnestly; "the process of elimination leaves that the only possible explanation of Justin's disappearance. He couldn't go up a chimney; he didn't go out of any door or window, and since he is not in the house, he must have left by some secret passage. Do you not agree with me?"
"I suppose so," said Mrs. Duncan, agreeing only because she had no other possibility to suggest.
"Well, if that's true," put in Mabel, "I'll find that secret passage! If there's one in this house, I'll find it. If there's anything in this secret passage idea, then it must be that Justin went through his secret door and the lock sprung, or something, and he couldn't get back. But he isn't hiding on purpose; and if he's walled up anywhere, I'll get him out if I have to pull the walls down!"
"Don't go to pulling the walls down, Mabel," said her husband; "when Mr. Crosby comes, he can tell us if there's any secret passage. I've often heard him say that he knows every nook and cranny of the whole place."
"Yes, he does," said Miss Abby; "as a child he was always rummaging around in the attics and cellars, and if there's any subterranean passage he'll know of it."
"Then there's nothing to do but to wait until Mr. Crosby comes," said Ernest Chapin, thoughtfully.
"But it seems awful to do nothing," said Fred Crane. "Suppose we telephone for a detective."
"Oh, mercy, no!" exclaimed Miss Abby, "I have a perfect horror of detectives! Do let us wait until Mr. Crosby and Mr. Gale come; I'm sure they can do something."
"I'm sure I don't know what they can do more than we can," declared Mr. Crane, who felt his own services unappreciated; "come, Mabel, let us go for a walk through the grounds,—we may find something by way of a clue."
The party dispersed, only to congregate again in small groups here and there, to discuss the mystery.
Ernest Chapin asked Dorothy to go out on the South Terrace with him for a little chat, and, after a moment's hesitation, the girl complied. They found themselves alone on the terrace, and Dorothy said, "You don't think, do you, Mr. Chapin, that Justin's absence has anything to do with last night's scene?"
"What scene do you mean?" said Chapin, looking exceedingly perturbed.
"Why, the scene he made when he found you and me out on the little balcony, looking at the moon."
"I wasn't looking at the moon," said Chapin, and he turned away his eyes as he added in a low voice, "I was looking at you."
"Never mind what you were looking at," said Dorothy, blushing a little. "He spied us while you were looking; and I'm asking you if you think that circumstance had anything to do with his disappearance."
"How could it?" demanded Chapin savagely. "Do you suppose he went off and hanged himself because
