Erskine opened the envelope, and took out a sheet of notepaper, on which were written just a few chemical formulæ and about forty words.
Castellan, who was watching him keenly, for the first time since they had sailed together through stress and storm under the White Ensign, saw him start. The pupils of his eyes suddenly dilated; his eyelids and eyebrows went up for an instant and came down again, and the rigid calm of the British Naval Officer came back. He put the letter into his hip pocket, buttoned it up, and said, very quietly:
"Thank you, Mr Lennard. You have done me a very great personal service, and your country a greater one still. I shall, of course, make use of this. I am afraid if you had sent it to the Ordnance Department you wouldn't have heard anything about it for the next three months or more; perhaps not till the war was over."
"And that is just why I brought it to you," laughed Lennard. "Well, here's good luck to you and the _Ithuriel_, and all honour, and God save the King!"
"God save the King!" repeated Erskine and Castellan, with that note of seriousness in their tone which you can hear in the voice of no man who has not fought, or is not going to fight; in short, to put his words into action.
They emptied their glasses, and as they put them down on the table again there came a knock at the door, sharp, almost imperative.
The head waiter threw the door open, and a Naval messenger walked in, saluted, handed Erskine an official envelope, and said:
"Immediately, sir. The steam pinnace is down at the end of the Railway Quay."
Erskine tore open the envelope and read the brief order that it contained, and said:
"Very good. We shall be on board in ten minutes."
The messenger, who was a very useful-looking specimen of the handy man, saluted and left the room. Castellan ran out after him, and they went downstairs together. At the door of the hotel the messenger put two fingers into his mouth, and gave three soft whistles, not unlike the sounds of a boatswain's pipe. In two minutes a dozen bluejackets had appeared from nowhere, and just as a matter of formality were asked to have a drink at the bar. Meanwhile Denis Castellan had gone into the smoking-room, where he found the sandy-haired, blue-eyed man still sitting at his table in the corner, smoking his cigar, and looking over the paper. He touched him on the shoulder and whispered, in perfectly idiomatic German:
