Washington Post sundial article

[Thaddeus Weakley]

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 Am! erican
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 eve! n 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
reti! red 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
s! undials 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
adv! ance 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."

  

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