Principles:
Hapkido's main principles are Yoo (flowing like water), Won (the circle, the perfect geometric shape), Hwa (harmony in no resistance). It also considers Seang-Ni-Hak (physiology), Meom (body), Shin (mind) and Shim-Ni-Hak (psychology).

Weapons:
Students learn to defend against a variety of weapons including knives, canes, rope, the staff (short, mid and long length), swords and other bladed weapons. They are also taught how to use everyday items as weapons of their own.

Techniques:
Hapkido uses a wide range of striking, joint lock, pinning and throwing techniques to avoid any narrow specialization. Grappling is also taught but the emphasis is on escaping to regain footing.

Footwork is essential and used with hand strikes and low level kicks when at a further range to bridge the distance. Once at a closer range the practitioner takes control of the opponents balance to apply a joint lock or throw the opponent depending on the situation.

Hapkido makes use of people's pressure points which can be struck to produce unconsciousness or immobility of limbs or manipulated to create pain. Using pressure points allows one to unbalance their opponent more easily.

Strikes and punches with both hands and elbows are taught. "Live hand" strike is also part of the Hapkido syllabus. It is a strike that focuses energy to the hand and allows the practitioner to produce energy and internal strikes to the opponent. Usually hand strikes are used to weaken the opponent's balance before joint locking or throwing but sometimes are used as a finishing technique.

Although Hapkido contains kicks from Karate and Tae Kwon Do the emphasis of these movements is still on Won; the circle. There are many sweeping or hooking kicks and there is greater commitment to the attack than to quick retraction of the leg. As students advance they learn blade kicks which are sweeping kicks that make contact with pressure points on the opponents body.

To get all the way from Japan to the USA the balloons where released in fall and winter when the jet stream across the Pacific Ocean was strongest. Being pulled along in the stream it took the balloons 3-4 days to make the journey across the Pacific. Once all the sand bags ran out two incendiary bombs were dropped the next time the altimeter registered the balloon as to low. Finally the bomb was dropped as, by the Japanese's calculation, it should be over the US by then. At this time a 64 foot fuse connecting the balloon to its cargo was ignited and about 82 minutes later the balloon itself became a flying fireball. Sometimes the balloon descended with the bomb and burnt up or failed to ignite at all.

The Japanese undertook the balloon bomb project in retaliation to the “Doolittle raid” (when American pilots bombed targets in Tokyo in 1942). Though it took 2 years to make the 9000 balloons they finally launched in November 1944. The goal was to cause fear among the public and government by executing such a long ranged attack and to divert the attention of the armed forces from the war by causing forest fires, destroying buildings and causing harm on home soil. Some of the bombs drifted over Canada and even made it near the Mexico border.

Though the bombs caused little damage they had the potential to be very effective and were shot down when sighted before reaching the mainland. There was also a concern that the Japanese might initiate biological or chemical warfare using the balloons. So, to discourage the launch of more balloons, the US applied censorship on the media; asking them not to mention any balloon bomb incidents. It worked rather well, the Japanese didn't hear of many successful bombings and this helped lead to them giving up on the project. Censorship was lifted to alert the public to the danger of the balloons when, in May 1945, six people (five children and a woman) were killed after they tried to pull a balloon from a tree. They are the only know casualties of the balloon bombs and the “only known fatalities on the U.S mainland from enemy attack during World War II.”

In April 1945 two of the three plants producing hydrogen for the balloons were bombed and Japan gave up on the project. Since then 325 remains have been found all over North America and Canada. However it is estimated that 1000 of the 9000 balloons launched made it across the Pacific. In 1955 one was found unexploded but still dangerous even after ten year of corrosion. The most recent discovery of balloon bomb remains was in 1992. There is the possibility that more unexploded bombs or remains lie in the deserts, forests, lakes and mountains of North America and have simply not been discovered yet.

References:
http://www.japaneseballoonbombs.com/
http://39th.org/39TH/hc/fugowarhazzard.htm
http://web.mst.edu/~rogersda/forensic_geology/Japenese%20vengenance%20bombs%20new.htm
http://www.findingdulcinea.com/news/on-this-day/May-June-08/On-this-Day--Japanese-WWII--Balloon-Bomb--Kills-Six-in-Oregon.html
http://en.wikipedia.org/wiki/Fire_balloon
http://www.stelzriede.com/ms/html/mshwfugo.htm

Derek De Solla Price:
In 1951 the British physicist and historian Derek Price went to Athens to study the fragments for himself. After eight years, eighty-two fragments and at least thirty gears later, he released findings based solely on visual inspection and measurements; the fragments were an intricate clockwork device used for astronomical calculations and predictions. In 1971 Price teamed up with Charalampos Karakalos to take x-ray and gamma-ray radiographs of the fragments. The results allowed Price to reconstruct a model of the mechanism. A rectangular box with three large dials, one on the front and two on the back, is the basic description of the model. Each of the dials had a different function. The one on the front measured the annual progress of the sun and the moon. Of the back two, one displays a four year cycle with a smaller dial to show the Metonic cycle (cycle of the moon that repeats every 19 years) and the other shows the lunar year.

Michael Wright:
Rather than form conclusions from Prices’ work Wright began a new study all of his own. Using a different form of x-ray he was able to gain a better understanding of the three dimensional position of the gears. Between 2002 and 2005 he created a different model. The model changed the function of both the back dials and shows how it could be a fully functional planetarium.


The Antikythera Research Project:
Since 2005 an team of researchers from around the world have been building on the foundations laid by Price. With help from Volume Graphics software, HP and X-Tek they managed to take another step forward in discovering the functionality of the mechanism using new technology to take 3D x-rays of the fragments revealing both the placement of gears and more surface inscriptions. A special piece of HP imaging equipment also allowed them to see more of the inscriptions and features on the surfaces. All of this led to another model being constructed.

The front panel shows a dial marked with the zodiac and solar calendar. There are two hands indicating the position of the sun and moon and a display that shows the current phase of the moon. The back panel of the mechanism has two large spiral displays. One for the Saros cycle (predicts centuries of eclipse activities) and one for the Callippic cycle (a period of 76 years, equal to 4 Metonic cycles, at the end of which, by omission of one day, the phases of the moon recur at the same day and hour).

There are also several small dials. One of these has no astronomical or scientific function at all and is simply of cultural function. The small quartered circle does a four year cycle and shows which of the Greek games are to be in that year.

Origins:
The Antikythera Mechanism is thought to have been made between 150 and 100 BC. No one can really say where or by whom the Antikythera Mechanism was made and they can only speculate as to why Greek treasure was aboard a Roman vessel. One theory suggests that a Corinthian was the maker of the mechanism because the Metonic calendar uses Corinthian month names like those inscribed on the device. Corinthian colonies included Illyria and Epirus in north-western Greece and Corcyra on Corfu. The Corinthian capitals were Syracuse and Corinth. Syracuse was home to Archimedes, so researchers have been tempted to believe that is where the mechanism originated. Even though Archimedes died before the device was created he was known to have constructed mechanical devices that showed astronomical events.

Rhodes was considered to be the centre of astronomical and technological thought and so links have been made there too. They built devices similar to those of Archimedes to sell to wealthy Roman buyers. This would also explain the mechanisms presence on the Roman vessel. Rhodes was also home to the inventor of early trigonometry and the first person to scientifically catalogue the position of the stars; Hipparchus. He developed a quantitative geometrical model for the first anomaly of the moon’s motion and it has been discovered that the Antikythera Mechanism includes a realization of this model. Thus many suggest either Hipparchus or someone from his school made the Antikythera Mechanism.

Nature international weekly journal of science has a good video here.

The Antikythera Research Project website also has an FAQ page here.


References:
http://www.age-of-the-sage.org/archaeology/antikythera_mechanism.html
http://www.antikythera-mechanism.com
http://itotd.com/articles/533/the-antikythera-mechanism/
http://www.world-mysteries.com/sar_4.htm
http://ccat.sas.upenn.edu/rrice/usna_pap.html
http://www.antikythera-mechanism.gr/
http://archaeology.about.com/od/bronzeage/ss/antikythera_7.htm
http://www.nature.com/nature/videoarchive/antikythera/
http://www.stomverbaasd.com/antikythera-device-an-ancient-greek-computer/