And he was in battle frequently enough. The shadow of his famous helmet, bearing a crescent moon, had fallen on scores of battlefields. And he was a successful general, serving first Hideyoshi in Korea, and then Ieyasu when he unified Japan.
Perhaps too successful. He was one of the most powerful daimyo in Japan, and the Tokugawa had suspected that he had ambitions to become something more than a mere daimyo . . . a shogun. They were particularly irritated when he sent his own embassy to the pope in faraway Rome. Still, they had grudgingly found him to be indispensable.
Tasman’s superiors were certain that Shogun Iemitsu had been ecstatically happy when he realized that he could give Masamune a position of immense prestige . . . thousands of miles away.
Masamune addressed the Dutch captain in slow but understandable Portuguese. “Please explain.”
“Explain what, milord?”
“The proposed sailing route. Look!” Masamune pointed to the globe that his aide had reverently placed in front of him. It was a duplicate, as near as skilled Japanese craftsmen could make it, of the “Replogle” globe presented to the shogun the previous summer.
“This is the world according to the wizards of Grantville that your people spoke of. Now look.” He held a string taut across the surface from Sendai, the capital of his han, to Monterey, California, then released it. “This is the shortest path, neh?”
Tasman nodded. “That’s true, milord. But it’s not a route we can easily sail.”
“No? But the globe shows that the currents are favorable. See—Masamune’s finger traced out a chain of dashed blue arrows on the globe—this is marked, ‘Kuroshio Current.’ ‘Kuroshio’ is Japanese, meaning ‘Black Stream.’ Our sailors know it well, it is very fast and very dark. The short route should also be a fast route.”
“May I touch it, please?”
Masamune swept his hand in a graceful arc from Tasman to the globe.
“There are two problems, milord. Here is the North Pole, at ninety degrees north latitude, and this is the equator, at zero degrees. These smaller circles are the lines of latitude. Sendai is at about thirty-eight, and the up-timers’ Monterey a little farther south. Now, may I have that string, please?” Masamune silently handed it over.
Tasman laid it down between Sendai and Monterey. “See how close it comes at the middle of the journey to the fifty-degree line? It will be very cold there.”
“Even in summer?”
“Even then. There are likely to be more storms, that far north. And there could be icebergs.” When Masamune failed to react, Tasman quickly explained, “great masses of ice, some larger than ships, that float in the water. Most of the ice is below the water, and can’t be seen. They are very dangerous to shipping.”
The Japanese captain interjected, “Excuse me, Great Lord, but I have heard of such floating ice. Each year, some wash up on the beaches of Hokkaido.” These icebergs in fact came from glaciers calving into the Sea of Okhotsk. The North Pacific was virtually free of icebergs, as those of the Arctic ran aground in the Aleutians, but none of the participants in the meeting knew this.
“And the second problem?”
“Staying on course. We steer by the compass. If we run down a latitude eastward, we just make our way east as best as the winds allow, and we can tell from the height of the sun at noon whether we are too far north or south.
“But if we take this path—and indeed your lordship is most astute to recognize that this is the shortest path—then we start on a northeast heading, and mid-cruise we are heading east, and near Monterey we must bear southeast.
“Alas, since we cannot tell our longitude—” the Dutchman moved his hand back and forth between Japan and North America—“that is, our easting or westing, we would not know when to change the course.”
Masamune stated at Tasman. “Why can’t you tell your longitude?”
“We could if we had a clock that could keep time even at sea. Then we could set the clock to Sendai time before departing.” Tasman turned the globe slowly. “This is how the Earth turns. As it turns, the sun seems to climb in the sky, then sinks. When the sun has reached its highest point in the sky, we call that noon. Noon will come earlier in San Francisco than in Sendai. En route, at noon, we would look at the clock to see what the time in Sendai was, that is, how much before noon. And from that we would know the distance in longitude.”
“And you cannot build such a clock?”
“We can’t. Our clocks use a pendulum to keep time, and the rocking of the boat plays havoc with it.” Tasman shrugged his shoulders. “Perhaps the up-timers can do better.”