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Though sundials have been around 3,000 years, William Andrewes (indicating the lateness of the hour in his garden in Concord, Massachusetts) is perhaps the first to build one showing the time in multiple places simultaneously. (Jared Leeds)

The Shadow Knows

Why a leading expert on the history of timekeeping set out to create a sundial unlike anything the world has ever seen

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The first time I met William Andrewes, several years ago, he was wearing an inexpensive wristwatch with the cartoon figures Tintin and Snowy running across the dial. Since Andrewes then served as curator of Harvard University's Collection of Historical Scientific Instruments, his whimsical watch cut a ridiculous contrast with the important timekeepers he maintained, exhibited and also used as teaching aids in his course, "Instruments of Time and Space."

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Since leaving Harvard, in 1999, Andrewes, who is 56, has given up wearing a watch at all. At home, in Concord, Massachusetts, he can tell time well enough by a dozen or so antiques he keeps in good working order, and he says that while traveling he finds time "publicly available." When I saw him in October 2004 at Sotheby's in New York, for the seventh and final auction of the holdings of the now defunct Time Museum—the world's most comprehensive assemblage of timekeeping devices, dating from 3000 b.c. to the present—he was relying on his cellphone to keep appointments. "It allows you to tell time to the nearest minute," he assured me, "which is fine for civic purposes, though not sufficiently accurate for setting another clock."

Andrewes bid on several lots during that three-day auction, and almost everything he purchased, whether for himself or a client, he was buying for the second time; as the Time Museum's curator from 1977 to 1987, he had shopped the world to increase its collection from 1,300 to more than 3,500 items. Andrewes and his wife, Cathy, seated next to him that day at Sotheby's, could tie dozens of the museum's pieces to significant dates in their courtship and marriage and the births of their two children. They felt a special fondness for the clock Will had been restoring when they met—a 19th-century Christian Gebhard astronomical and automaton clock with 17 dials, 2 revolving globes, barometer, planetarium, date displays and figures performing each quarter and hour (including a religious procession every day at noon and a herald blowing a trumpet at midnight on New Year's Eve)—but it is nearly ten feet tall, more than eight feet long and far beyond their means. It sold for $142,400.

Despite Andrewes' long fascination with complex mechanical clockworks, he has recently taken what might seem a giant leap backward to become a "dialist," or maker of sundials. "My original goal in this," he said in response to my surprise, "was to produce an accurate timepiece with no moving parts—an original creation that combined art and science, drawing from the long traditions of both in its design, and incorporating the finest craftsmanship and latest technology in its construction." What really set his idea apart, however, was his intention to base the dial on an unusual type of map, and to center the map on the very spot where the dial would stand. The map's meridians of longitude would serve as the sundial's hour lines, creating a union of time and space for that particular location—something no dialist or clockmaker had ever before achieved.

A sundial is one of the oldest—it may be the oldest—of all scientific instruments. It depends on the Earth's rotation, although when it was first contrived, probably before 1500 b.c., its makers believed that the Sun revolved around a stationary Earth. Either way one envisions the heavens, the practice is the same: the Sun shines on the dial, and a protruding "gnomon" (from the Greek for "one who knows"—presumably one who knows what time it is) casts a shadow among the hour lines marked on a dial plate, indicating the time. What could be simpler? Or rather, what could be more deceptive than the apparent simplicity of this device? For in order to make the fallen shadow even approximate the correct time, the dial must be laid out with regard to latitude north or south of the Equator where it is to be used, respecting the changing high point of the Sun in the sky from day to day over the course of the year and the variable speed of the Earth's annual motion. There is nothing obvious about the construction of a proper sundial. Anyone who buys a mass-produced sundial and sets it out among the flower beds as a decoration should not be surprised to find that it fails to work.

The great variety of dial designs through history, according to the late science historian Derek de Solla Price, attests to the "aesthetic or religious satisfaction" that dialists must have derived from trying to simulate the heavens. Vitruvius, architect of ancient Rome, counted at least 13 dial styles already in use in Greece by 30 b.c. Then as now, a dial could be mounted vertically on the side of a building or set horizontally on a pedestal or the ground, and take virtually any shape—flat, spherical, conical or cylindrical. Some sundials were stationary, others movable, and many, like a sundial George Washington carried, were meant to fit in a pocket. Although weight-driven mechanical clocks were introduced in England around 1280, and became fixtures of public and private life by the 1600s, their proliferation sparked a boom in sundials. In the 1700s, after the inventions of the pendulum clock in The Hague and the balance spring in Paris inaugurated the era of precision timekeeping, sundials achieved even greater importance than before. "Just as the computer increased the need for the paper that some people thought it would replace," Andrewes says, "clocks—and later watches—greatly increased the demand for sundials, because every timekeeper needs, at some point, to be set correctly." A clock or watch may keep time, but only a sundial can find time—a distinctly different function—by deriving the hour from the relative positions of the Earth and Sun.

Today the work of measuring precise time has been relegated to government agencies such as the U.S. Naval Observatory in Washington, D.C., the International Earth Rotation Service at the Paris Observatory and the Bureau International des Poids et Mesures in Sevres, France, all of which measure a second by the interval it takes a cesium atom to vibrate 9,192,631,770 times. Because the Earth goes its own way in space, however, heedless of atomic time, "leap seconds" are periodically added to our years to keep our clocks in sync with the turning of our planet. A sundial requires no such adjustment. "A sundial lets you see the Earth turn," Andrewes says. "Of course you know it's turning, but when you witness the shadow moving across the dial you feel something. Many people have no idea why the seasons occur—that the hemisphere tilted toward the Sun actually changes from winter to summer. Time has become separated from space, and I think that's a mistake."

Andrewes' workshop, in the basement of his family's colonialstyle home in Concord, accommodates a 3,000-volume reference library, banks of file cabinets, a desk with a computer and other office equipment, a conference table and his drafting table, lathe and workbench. Sundial parts lie everywhere, along with an accumulation of clocks he has bought, or built himself, or saved for sentimental reasons, such as a 19th-century cuckoo clock that belonged to his parents—the first clock he ever took apart.

Though clocks surround him, Andrewes says he doesn't pay that much attention to time. "Clockmakers are the least time-conscious people," he says, "because in the end it does not matter how much time it takes to build a timepiece, but only that it turn out beautifully and show none of the angst that went into it. Engineers are happy if they make something that works, and many tend not to care what the inside bits look like, but clockmakers attend to all the hidden details, even on parts that will never be seen unless the clock is dismantled. To be a clockmaker is to work not just for yourself or your client, but also for someone else far in the future, someone who knows enough to judge your work, and who will look at something you've made someday and—you hope—say, ‘That was done right.'"

As a teenager in North London, where Andrewes spent school vacations assisting a local clockmaker, his hero was John Harrison, the 18th-century clockmaker who solved the problem of finding longitude at sea by creating the first accurate marine chronometer. By age 19, Andrewes had befriended Harrison's biographer, Humphrey Quill, a past master in the Worshipful Company of Clockmakers, a guild. Quill, by then elderly, placed Andrewes under the guidance of world-renowned watchmaker George Daniels, and also entrusted the youth with an unfinished Harrison clock—an early wooden regulator abandoned around 1720—for him to complete as his formal initiation into horology, the science of precision timekeeping. After Andrewes graduated from the Kingston College of Art in 1972, he taught design, clockmaking and metalwork at Eton College. The commission he won from the Royal Mint to create three medals commemorating the 300th anniversary, in 1975, of the Royal Observatory, in Greenwich, led to his taking charge of the observatory's historical collection of chronometers and precision clocks.

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