In the garden of Tudor Place, the house museum in Georgetown, an 18th-century sundial is framed by a saying that begins: "With warning hand I mark time's rapid flight."
Except, it doesn't. Or not with any useful precision.
Pocket sundials: Accurate when the sun shone.
(Offentliche Kunstsammlung Basel)
As anyone who has purchased or admired sundials knows, they look great but are lousy timekeepers. In theory, the shadow cast by the upright marker is supposed to fall on a horizontal dial divided into hours. As the sun crosses the sky, the shadow moves around the face to the appropriate marked hour. But don't set your watch by it.
"They are garden decorations," said Dave Kreiner, a sundial maker in Cedarburg, Wis. "They have nothing to do with telling time." Kreiner, who owns a company called Accurate Sundials, is among a cadre of sundial experts who, separately, are trying to restore the sundial as the precise celestial instrument it once was.
The problem: Sundials must be tailor-made for their location, and generic antique reproductions are not. Instead, they are built typically to show time at a latitude of 40 degrees, roughly the midline of the United States between Philadelphia in the east and Northern California in the west.
This may not matter to people drawn to the garden to escape the clock, who find a sundial merely a gracious ornament and are charmed by the notion of tracking the loose passage of the day as told by the sun. The same plume of fountain grass ignited by the morning sun forms dark blades with dazzling edges toward twilight. That connection to the natural world is much of the value in gardening.
But the sundial's laxity does matter to others, especially because it can be fixed. "Everyone is fascinated when they see a sundial actually working," said Frederick W. Sawyer III, president of the North American Sundial Society. "In the home garden, it would be nice for people to set them up so they actually work."
You can make a mass-produced sundial a little more accurate by correcting its orientation north, and even tilting the pedestal it is on, but for one of far more accuracy you will need to get a better dial.
First, the angle of the sundial's slanting shadow maker, which is called a gnomon, has to match the latitude it is in, approximately 39 degrees north in Washington. The angles between the hour marks must also be arranged for one's latitiude.
Also, the noon mark on the dial must be oriented to true north.
Even then, the sundial will not precisely match the clock. Every day, the sun reaches its high point in the sky, the moment known as the meridian: Hence the designation of a.m. (ante meridiem) and p.m. (post meridiem). The meridian occurs at a different moment within a single state, or even a single Zip code: The solar noon in Annapolis will occur before the one in Rockville, and accurate sundials in each locale would show noon at different times.
Time zones were invented in the 19th century to bring uniformity in an industrial age, and each of the world's 24 time zones has one fixed average meridian. In the Eastern Standard Time zone, it is at longitude 75 degrees west, just to the east of the Delmarva Peninsula. Hence we now exist in two temporal worlds: sun time and clock time.
"Our mentality changed at the beginning of the 20th century," said Sawyer. "It's another way of noticing how we are being removed from nature."
Kreiner seeks to correct sundial accuracy with gnomons and dials customized to specific locations. Look at his Web site, www.accuratesundials.com, and you will see how dials and gnomons differ by state. Models in aluminum, copper, brass and granite range in price from $259 to $599.
They are made either to record standard time or daylight saving time; he recommends the latter because most people are in the garden in summer. You cannot simply rotate a sundial pedestal to put your sundial forward or back.
Even a sundial built for your garden does not account for another variable of solar time: The sun does not keep a precise 24-hour day. Sometimes it is early, sometimes late, by a few seconds or minutes depending on the time of year. This is related to the Earth's tilted axis and its elliptical orbit around the sun. For sundial scholars, this produces something called the equation of time, and it means that even an accurate sundial will gain 16 minutes in the weeks leading to Halloween and lose almost 15 minutes by Valentine's Day.
It is a variation of little consequence either to the sun, the Earth or, for most of human history, the people upon it. Even when we tried hard to measure time with such things as primitive sundials and, later, clocks, solar time remained something to be regarded and followed. When you bought a wind-up clock in the 19th century, you got a little sundial to place on your windowsill so that each solar noon, you could correct the errant mechanical timepiece, said Sawyer.
Now, though, as we strive for ever greater precision, it is solar time that is faulted for its inaccuracy. Indeed, we care not for solar noon anymore, but set our clocks by an atomic chronometer in Boulder, Colo., that measures time by aiming lasers at a fountain of cesium atoms and getting them to glow back. Its owner, the National Institute of Standards and Technology, says it is accurate to within a second every 20 million years. It is the godclock, bestowing truth and purpose on all other timepieces on the planet.
But just as clocks can be improved, so too can sundials. Sawyer, a retired actuary in Glastonbury, Conn., has devised a sundial within a sundial: Its inner scale measures sun time, the outer one clock time.
Like Kreiner and Sawyer, a sundial maker in Burlington, Vt., named Bill Gottesman has been striving to improve the precision of sundials, and says his patented Renaissance sundial accounts for all the variables the sun can throw at it (www.precisionsundials.com).
It is a handsome solution, a large, bronze helix designed so that time is not marked with a shadow but by light, using a spine of specially milled glass beads to create a reflective mirror. Its band of light travels once around the helix in 12 hours at a rate of six inches per hour. The base is adjustable for latitude, and a sliding scale within the helix corrects for the equation of time as well the switch from daylight saving to standard time.
Gottesman, 47, a retired physician, has long harbored an interest in sundials along with the question of why they wouldn't tell the time.
His Renaissance model, he says, is so accurate "you could schedule your day around it." It sells for $8,000, and so far he has sold nine of them. He also makes a sundial based on Sawyer's compensating sundial principal. Made of bronze and granite, it sells for $1,800.
This quest for sundial accuracy is not new. In the old days, when sundials were serious timekeepers, they were designed for specific locations and kept a fairly accurate measure of the hours.
George Washington had a locally accurate sundial at Mount Vernon in the 1780s, said Robert Kellogg, a physicist from Rockville and registrar of the sundial society. The weathered original is displayed in the mansion, a replica sits on a pedestal in the west courtyard. Reproductions sold at Mount Vernon, thus, are locally accurate.
Kellogg may trump it. He has one of the few surviving examples of a pocket sundial. It was made around 1720 by Johann Willebrand, one of two pocket sundial makers active in the German city of Augsburg. Made of brass and silver, it weighs about two ounces, fits in the palm of the hand, and is adjustable for latitude.
You find north by a compass in its base. The dial is a ring attached at right angles to an upright scale and can be moved to the appropriate latitude reading. The dial gives the latitudes of major European cities, and the piece was made, probably, for a wealthy patron who would travel between capitals in Europe, said Kellogg. Curiously, it has a bead of brass on the scale at the 38th parallel, too far south for most of Europe. Kellogg thinks it was a benchmark for a colonial settlement, possibly Williamsburg, and that it was made for an American client. It is currently on display at Homewood House Museum in Baltimore as part of a show on clock making in early Maryland. (On Saturday, Kellogg lectures at the museum on colonial American sundials, at 11:30 a.m. For information call 410-516-5589, www.jhu.edu/historichouses/.)
The sundial at Tudor Place, a mansion built by the Peter family at Q and 31st streets, NW., was retrieved from the Peter's ancestral home in Scotland in the early 20th century. It forms the centerpiece of the boxwood knot garden. Kellogg said members of the sundial society calculated that the hour markings were geared to around 48 degrees north, nowhere in the British Isles but close to Augsburg. "Of course," he said, "it would never tell time" correctly in Scotland or Georgetown.
This does not diminish its delight as the decorative heart of a formal but serene and relaxed pleasure garden. Wander Tudor Place, or indeed your own garden, and there are signs everywhere that sun time still reigns if we let it. You know that the meridian is lower each day in the advance to the winter solstice, and that its backdrop alters as well. Soon, the fall light will be soft but limpid. In winter, azure skies streaked by vapor trails will bring a bone-chilling cold and leaden skies will herald snow. Faint, ghostly shadows will play on the face of the sundial and accuracy no longer seems to matter.
Sun time may be fast and loose, but as an inscription on a sundial at the historic Hampton estate in Towson, Md., points out, it is still "more sacred than gold."