The Moghul

the Hindu quarter had erupted soon after, forcing Mukarrab Khan to remove the English seamen outside the town walls, in tents erected by the "tank," the city reservoir.
    Yes, Hawksworth sighed, it'll be a long time before India forgets her first taste of the English.
    The barge bobbed lightly as two Indian porters, knee-deep in the mud, hoisted the first roll of woolen cloth onto the planking. This begins the final leg of the India voyage, Hawksworth thought to himself. And this has been the easiest part of all.
    Almost too easy.
    Pox on it, believe in your luck for a change. The voyage will post a fortune in pepper. Lancaster was knighted for little more than bringing home his vessels. He reached Java, but he found no trade. He'd have sailed home a pauper if he hadn't ambushed a rich Portuguese galleon in the harbor at Sumatra.
    How many weeks to a knighthood? Three? Four? No, we'll make it in less. We'll man every watch. Woolens aland, cotton out. I'll have the frigates laded, stores on board—we can buy cattle and sheep from villages up the coast—and all repairs completed in two weeks. I'll have both frigates in open seas inside a fortnight, where not a Portugal bottom afloat can touch us.
    And if permission for the trip to Agra comes, I'll be out of Surat too.
    If I live that long.
    He reached into his belt and drew out a long Portuguese stiletto. An elaborate cross was etched into the blade, and the handle was silver, with a ram's head at the butt. The ram's eyes were two small rubies. He had been carrying it for two days, and he reflected again on what had happened, still puzzling.
    He had returned to the observatory the next morning after he had met Shirin, and this time he brought his lute. But she did not come. That morning, or the morning after, or the morning after. Finally he swallowed his disappointment and concluded he would not see her again. Then it was he had gone to work cleaning away the moss and accumulated mud from the stone instruments. Parts of some seemed to be missing, and he had searched the hut for these without success. All he had found was a hand-held astrolabe, an instrument used to take the altitude of the sun. But he also found tables, piles of handwritten tables, that seemed to hold the key to the use of the instruments. His hopes had soared. It seemed possible, just possible, that buried somewhere in the hut was the key to the greatest mystery of all time—how to determine longitude at sea.
    Hawksworth had often pondered the difficulties of navigation in the deep ocean, where only the sun and stars were guides. They were the primary determent to England's new ambition to explore the globe, for English navigators were still far less experienced than those of the Spanish and Portuguese.
    The problem seemed overwhelming. Since the great earth was curved, no line on its surface was straight, and once at sea there was absolutely no way to determine exactly where you were, which way you were going, or how fast.
    The least uncertain measurement was probably latitude, a ship's location north or south of the equator. In the northern hemisphere the height of the polestar was a reasonably accurate determinant of latitude, although it was a full three degrees distant from the northernmost point in the sky. Another measure of latitude was the height of the sun at midday, corrected for the specific day of the year. The problem lay in how to measure either of these elevations accurately.
    A hundred years before, the Portuguese had come across an ingenious Arab device for telling the elevation of the sun. It consisted of a board with a knotted length of string run through the middle. If a mariner held the board vertically and sighted the horizon at one end and some object in the sky at the other, the length of the string between the board and his eye could be used to calculate the elevation of the object. In a short time a version appeared in Europe—with a second board replacing the string—called the cross-staff.
    However, since locating both the horizon and a star was almost impossible at any time except dawn or dusk, this device worked best for sighting the sun—save that it required staring into the disc of the sun to find its exact center. Also, the cross-staff could not be used when the sun was high in the sky, which was the case in equatorial waters. Another version of the cross-staff was the astrolabe, a round brass dial etched with degree markings and provided with a movable sight