He picked up a bottle of something with a faint greenish tinge.

“See the bands gradually fade?”

I watched, and indeed they did diminish in intensity and finally disappear, leaving an uninterrupted and brilliant spectrum.

“My spectroscope,” he said, simply, “shows that the blood-crystals of Barnes are colorless.  Barnes was poisoned—­by some gas, I think.  I wish I had time to hunt along the road where the accident took place.”  As he said it, he walked over and drew from a cabinet several peculiar arrangements made of gauze.

He was about to say something more when there came a knock at the door.  Kennedy shoved the gauze arrangements into his pocket and opened it.  It was Maude Euston, breathless and agitated.

“Oh, Mr. Kennedy, have you heard?” she cried.  “You asked me to keep a watch whether anything more happened to Mr. Barnes.  So I asked some friends of his to let me know of anything.  He has a yacht, the Sea Gull, which has been lying off City Island.  Well, last night the captain received a message to go to the hospital, that Mr. Barnes wanted to see him.  Of course it was a fake.  Mr. Barnes was too sick to see anybody on business.  But when the captain got back, he found that, on one pretext or another, the crew had been got ashore—­and the Sea Gull is gone—­stolen!  Some men in a small boat must have overpowered the engineer.  Anyhow, she has disappeared.  I know that no one could expect to steal a yacht—­at least for very long.  She’d be recognized soon.  But they must know that, too.”

Kennedy looked at his watch.

“It is only a few hours since the train started from Halifax,” he considered.  “It will be due in New York early to-morrow morning—­ twenty million dollars in gold and thirty millions in securities—­ a seven-car steel train, with forty armed guards!”

“I know it,” she said, anxiously, “and I am so afraid something is going to happen—­ever since I had to play the spy.  But what could any one want with a yacht?”

Kennedy shrugged his shoulders non-committally.

“It is one of the things that Mr. Lane must guard against,” he remarked, simply.  She looked up quickly.

“Mr. Lane?” she repeated.

“Yes,” replied Kennedy; “the protection of the train has fallen on him.  I shall meet the train myself when it gets to Worcester and come in on it.  I don’t think there can be any danger before it reaches that point.”

“Will Mr. Lane go with you?”

“He must,” decided Kennedy.  “That train must be delivered safely here in this city.”

Maude Euston gave Craig one of her penetrating, direct looks.

“You think there is danger, then?”

“I cannot say,” he replied.

“Then I am going with you!” she exclaimed.

Kennedy paused and met her eyes.  I do not know whether he read what was back of her sudden decision.  At least I could not, unless there was something about Rodman Lane which she wished to have cleared up.  Kennedy seemed to read her character and know that a girl like Maude Euston would be a help in any emergency.