What are Anniversary clocks?
Are you fascinated with the unique mechanism that drives and runs your antique 400 day anniversary clock?
Do you want to know how a single wind can make it keep accurate time for a year? Read on and discover all essential information regarding anniversary clocks.
Some people may regard to anniversary clocks as a sole gift item but actually it is a specific clock type, and a very popular kind of antique clock favored by most clock collectors due to its highly unique mechanism.
They are so named because of their capacity to last more or less a year, on a single winding thus justifies their former label, 400-day clocks.
These time teller achieved popularity for 2 distinct reasons, primarily because they require very little attending. Once set, wound, and adjusted, torsion clocks can then keep accurate time for a year.
Another aspect is that 400 day clocks mark special occasions and have graced to crown important milestones and events such as birthday and of course anniversaries. They are not necessarily gift items but have become greatly ideal in this aspect.
Due to its ability to charm their way onto memorable celebrations, anniversary clocks have come to be also known as the occasion, commemorative, even awards clock.
Identifying anniversary clocks
Antique anniversary clocks are table top and mantel clocks housed in a glass or crystal case which allows its inner workings to be practically visible.
Just like longcase clocks; these timepieces are often made to stand freely on a leveled surface.
400 day clocks can be easily distinguished thru a glass dome that houses the main clock display. The glass casing is removable which allows cleaning the clock’s inside movement.
Anniversary clocks are typically made up of glass, crystal and brass with either three or four brass balls that whirls beneath the clock face. The clock display is often circular and some vintage anniversary clocks even have handles on top.
A series of dangling chimes hangs from the clock display. These chimes are commonly made out of glass or a metal such as brass which rotates while the clock runs.
How does an anniversary clock work?
400 day clocks are mechanical clocks that require the use of a torsion pendulum; hence they too are called torsion clocks or torsion pendulum clocks.
Instead of typically swinging right and left, the pendulum rotates clockwise and counter-clockwise and is the main reason why it consumes less energy allowing the clock to function for a year without constant human intervention.
Torsion pendulums are weighted disks or wheel that is often decorative and is composed of 3 or 4 chrome balls or ornate spokes, suspended by a thin wide or ribbon called a torsion spring. It was first invented by Robert Leslie in 1973.
A weighted disk is attached to the torsion spring that powers the clock’s gears as it twists. An anniversary clock’s design works much the same way as a watch’s balance wheel and hairspring.
The internal gears of an anniversary clock energizes the torsion spring. Torsion clocks such as 400 day clocks are usually delicate and temperature and humidity fluctuations alters the elasticity of the suspension spring thus they keep inaccurate time.
However, Charles Terwilliger invented a suspension spring in 1951 that overcame the problem, thus improved the performance of later produced anniversary clocks.
Brief history of anniversary clocks
The anniversary clock was first invented and patented in 1841 by an American, Aaron Crane. But Anton Harder, a German clock maker claimed to have created it in 1879 with his idea for the winding mechanism taken from watching servants light the candles on a rotating chandelier.
In 1901, an Ohio clock making company Bowler & Burdock copyrighted the term “anniversary clock” which had become the popular name for what then was referred to as the “400-day clock”.
Its descriptive name was derived because it was the first mechanical clock that need not be wound daily.
The anniversary clock was one of the first clocks to resume production after World War II. Thousands of GI’s brought them back as souvenirs that can be easily purchased at the Post Exchange.
125 different styles of old anniversary clocks were manufactures by about 13 anniversary clockmakers, each with a unique suspension system back then. However, in 1965 the number of clock makers dropped to 5 making repair parts very difficult to find.
Because of this, the battery-operated Anniversary clocks soon materialized, replacing physical winding and resulted to the addition of sound and crystal balls.
Original antique anniversary clocks you can find today are mainly family heirlooms and treasured pieces of collection owned by serious clock collectors.