He threw open the door of his private office. A shallow mahogany case, about a foot square, locked and sealed, was sunk into the opposite wall. Salt knocked off the wax and opened the case with a key which he took off the ring and gave to Orr-Evelyn as he spoke. Inside the case were a dozen rows of little ivory studs, each engraved with a red number. Fastened to the inside of the lid was a scale map of the land lying between the outer wall and the wire fence. Every stud had its corresponding number, surrounded by a crimson circle, indicated on the plan.
"If the entanglement should be carried you will take no further risk," continued Salt. "Captain Ford will give you the general indication of the attack from the lantern. There are two men detailed to each block of mines who will signal you the exact moment for firing each mine. Those are the numbered indicators above the box. Good-bye."
He paused at the door; time was more than life to him, but he had an ordered thought for everything.
"If you hear no more of me, and what might be imagined really troubles you, Evelyn, you can make use of this," he remarked, and laid the telescript he had received upon a table.
It was not the time for words, written or spoken, beyond those of the sheerest necessity. Half an hour passed before Orr-Evelyn had an opportunity of glancing through the letter that had called Salt from his post. When he had finished it he took it down, and read it aloud to the headquarter staff amidst the profoundest silence, in passionate vindication of his friend and leader. This was what they heard:
"Unity League, Trafalgar Chambers.
"The building is surrounded by mob. Seaton Street, Pantile Passage, and Pall Mall and the Haymarket, as far as I can see, densely packed with frantic men. All others in building had left earlier. I shall remain. Wires cut, and fear that you may not receive this, as other telescribe messages for help unanswered. Mob howling continuously for Sir John Hampden and Mr Salt; dare not look out again, stoned. Shall delay advance, doors and stairs, as long as possible, and burn all important League books and papers last resource.
"Good-bye all, my dear friends.
"Irene Lisle."
CHAPTER XIX
THE "FINIS" MESSAGE
The storm had not decreased its violence when, three minutes later, Salt stood unperceived on the broad coping outside an upper storey of the tower, and, sinking forward into the teeth of the gale, was borne upwards with rigid wings as a kite ascends.