7 OF THE WORLD'S MOST AMAZING CLOCKS

7 of the World's Most Amazing Clocks
By Laura Kiniry, Popular Mechanics, 26 February 2013.

They're advanced, artistic, and a sight to behold - not to mention incredible ways of marking time. From Denmark to Japan, we introduce you to some of the world's most interesting public clocks. Take a little time to take in these timepieces.

1. The Water Clock, Osaka, Japan

Japan's Osaka Station City is filled with public clocks, but there's one timepiece that's more striking than most: the Water Clock in the complex's South Gate building, by Japanese mechatronics manufacturer Koei Industry. A work of high-tech art, the Water Clock delivers digital time using H₂O and space printing. At the top of the clock are 400 computer-controlled nozzles that dispense water in both pre-programmed patterns, in shapes such as musical notes, and as a numeric display of the actual time. After the water falls and tells the time, it collects in a basin at the bottom of the clock to be recirculated into the system. Altogether the clock requires 30 litres of water per minute.

2. Iron Ring Clock, Hamilton, Ontario, Canada

Credit: Burtonpe/Wikipedia

Four Canadian engineering students created the Iron Ring Clock as their thesis project in 2003. The nearly 5-foot-tall timepiece is now on display at their alma mater, McMaster University in Hamilton, Ontario. The clock, named for the rings most Canadian engineering students wear upon graduating, uses a synchronous electric motor, which synchronizes with the frequency of electricity it receives. Two stainless steel rings more than 3 feet in diameter rotate independently. The lower ring displays the minutes, while the upper ring, which displays the hour, uses a Geneva-drive mechanism to slow down its rotation. The rings are decorated with 6-inch-high numbers that, when read straight on, tell the time. A stained-glass portrayal of the McMaster crest stands between the two rings, doing double duty as a school symbol and as a cover for the clock's mechanical drives and power-transmission systems. [More]

3. Jens Olsen's World Clock (Verdensur), Copenhagen, Denmark

Jens Olsen's World Clock, built in the mid-20th century, displays more than time. It also calculates current astronomical information such as the relative positions of the sun, moon, and stars. The titanic timepiece features a dozen clockworks showing the exact time at locations around the globe and features more than 14,000 parts, including displays for lunar and solar eclipses and the time equation (the time difference between local time and solar time, or the Earth's position proportional to the sun). Verdensur (as it is also known) is a mechanical clock, meaning it uses a repetitive oscillator and a controller device, which replaces the energy the oscillator loses to friction and converts its oscillations into countable pulses to tell time. Its fastest gear takes 10 seconds to complete a revolution; its slowest, 25,753 years. Olsen, the Danish locksmith who designed the machine, died a decade before it was completed, but the clock still stands in Copenhagen City Hall. [More here and here]

4. Cosmo Clock 21, Yokohama, Japan

Credit: ajari/Flickr

While not much in the way of technological advancements as far as clocks go, Japan's Cosmo Clock is impressive for both the structure's overall size (369 feet tall, including its base, with a diameter of 330 feet) and the fact that it's also one of the world's largest Ferris wheels. Built in 1989 and now located in Yokohama's Cosmo World theme park, the wheel features 60 eight-person passenger cars and a massive time display at its central hub. While it's said to be the world's largest clock, it's a bit of a misnomer because most estimates include the actual wheel on which it's based. Still, the giant timepiece - which is really just a huge digital clock slapped onto a Ferris wheel - is an undeniable landmark. The structure is especially impressive during evenings, when it lights up in a fireworks-like display of neon colours such as gold, blue, or pink (depending on the season). [More here and here]

5. Corpus Clock, Cambridge, England

Credit: Rror/Wikimedia Commons

British physicist Stephen Hawking unveiled the mechanically driven Corpus Clock (invented by his colleague John C. Taylor) in 2008. Situated on the campus of England's Cambridge University, at Corpus Christi College, the unusual timepiece features a 24-karat-gold-plated disk nearly 5 feet in diameter that displays time through a series of 60 backlit slits. The slits are arranged in three steel rings, each one encircling the next. As the rings move they reveal a series of blue LED lights, which mark the hours, minutes, and seconds. By design, the clock is accurate only once every 5 minutes, reminding viewers of time's irregularity (typical Hawking). The rest of the time, the flashing LEDs (there are 2,736 of them in all) are just for show.

Perhaps the clock's coolest feature is the eerie Chronophage, or "time eater," which sits atop the disc. This fanged-tooth metal insect rocks back and forth on articulated hinges, literally chomping away at the passage of time. The Corpus Clock also features the world's largest grasshopper escapement - an 18th-century invention that transfers energy to the clock's pendulum to replace what's lost to friction during its cycle. Both the escapement and the clock's toothed escape wheel (the part that engages regularly with the pendulum to move the clock's "hands") are prominently displayed on the front of the timepiece rather than at the back, where they are traditionally hidden from public view. [More here and here]

6. Giant Water Clock, Indianapolis, USA

Water clocks are some of the world's oldest time-measuring devices. French scientist and artist Bernard Gitton built this modern version of the instrument in 1988. Displayed in the Children's Museum of Indianapolis, it's 26.5 feet tall - making it North America's largest water clock - and features more than 40 glass and 100 metal pieces.

Instead of pure water, the clock operates on a solution of deionized water, methyl alcohol, and blue dye. The dye makes the water easy to see; using deionized water keeps it electrically nonconductive; and the alcohol prevents bacteria growth.

Here's how it works: A basement pump sends the solution up through the clock's central pipe into a reservoir atop the timepiece, from where it drips onto a scoop. With a swing of the clock's pendulum, the scoop pours water into a series of siphons, or inverted U-shaped tubes. As more water falls, the H₂0 already in the tubes rises, ultimately emptying into a series of small glass globes, each one representing 2 minutes. Once all 30 small glass globes reach capacity, they empty and a larger hour globe fills.

To calculate the time, figure out the hour by counting the number of filled larger globes, seen here on the left. For minutes, count the filled smaller globes (on the right) and multiple by two. [More here and here] [Video]

7. Clock of the Long Now, Texas, USA

Credit: Pkirlin/Wikimedia Commons

Inventor and scientist Danny Hillis conceived of the Clock of the Long Now - also called the 10,000-Year Clock - as a way to promote long-term thinking. The full-scale clock, which will stand nearly 200 feet tall and is designed to keep time for 10,000 years, is currently being constructed inside a mountain in western Texas as a project of the Long Now Foundation, a non-profit established in 1996. Though there's no word as to when the clock will be completed, the original 8-foot-tall prototype is currently on loan to and display at the Science Museum of London.

Hillis has had to get creative to build a timepiece that keeps ticking for 10,000 years. The clock will undoubtedly require maintenance, so he decided that it should require human winding - it's unlikely that any other power source would be around for 10,000 years. As he couldn't find a timing mechanism that would be both reliable and accurate, Hillis used two - one that's reliable but not accurate, and the other vice versa - linked together in what's called a phase-locked loop: a type of electronic circuit that matches the phase of an input signal with the one derived from its output oscillator to keep the two in balance. To calculate time, the 10,000-year clock will use binary digital logic that's mechanically (rather than electronically) implemented through a sequence of stacked binary adders, and time will be displayed using five digits (i.e., 02013) instead of the standard four.

The forward-thinking timepiece - which will be displayed on land open to the public - will include astronomical elements as well. [More] [Long Now Foundation website]

[Source: Popular Mechanics. Edited. Links added.]