“We are making good progress,” said Fitz. He held a peculiar device at his side that combined a small telescope and a tiny, ten-line abacus of screw-thread beads. Hereward had never seen any other navigator use such an instrument, but by taking sights on the moons and the stars and with the mysterious aid of the silver chronometric egg he kept in his waistcoat, Fitz could and did fix their position most accurately. This could then be checked against the directions contained with the salt-stained leather bindings of the dark rutter.

“Come to the taffrail,” whispered Fitz. More loudly, he said, “Keep her steady, helm. I shall give you a new course presently.”

Man and puppet moved to the rail at the stern, to stand near the great lantern that was the essential beacon for the following ship. Hereward leaned on the rail and looked back at the Strongarm again. In the light of the two moons the bomb vessel was a pallid, ghostly ship, the great mortar giving it an odd silhouette.

Fitz, careless of the roll and pitch of the ship, leaped to the rail. Gripping Hereward’s arm, he leaned over and looked intently at the stern below.

“Stern windows shut—we shall not be overheard,” whispered Fitz.

“What is it you wish to say?” asked Hereward.

“Elements of our plan may need re-appraisal,” said Fitz. “Fury is no easy dupe and once the Sea Gate falls, its nature will be evident. Though she must spare me to navigate our return to open water, I fear she may well attempt to slay you in a fit of pique. I will then be forced into action, which would be unfortunate as we may well need the pirates to carry the day.”