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Japanese history shows us a nation that was closed off in traditionalist feudalism until the 16th century, living in complete physical and intellectual isolation. It was only then that the West began to come into contact with Japan’s thousand-year-old culture, which was rich in refined traditions, but devoid of mechanical clocks. There were no antique Japanese clocks.
The introduction of mechanical clocks
According to legend, Saint Francis Xavier (1506–1552) presented Shogun Tokugawa Ieyasu with a mechanical lantern clock. Local technicians studied this simple model and developed ancient Japanese clocks based on it. The pendulum had not yet been invented.
In 1639, Japan began a new period of cultural isolation from foreign countries, which lasted for over two centuries. As a result, ancient Japanese clocks continued to be inspired by solutions that had been superseded in the West, but which were ingeniously adapted to the unique local method of measuring time.
The tradition of counting hours in Japan
A day consisted of twelve hours, with six hours of daylight and six hours of darkness. Each Japanese hour was equivalent to two Western hours. Japanese hours were counted in descending order from 9 to 4, from noon to midnight. However, hours from 1 to 3 were not used for religious reasons, as Buddhist monks traditionally used the chimes from 1 to 3 to call people to prayer.
This reverse order derived from an ancient method of measuring time using lit incense sticks, which burned down and became shorter as time passed. Dawn and sunset corresponded to 6 o’clock in the Japanese system.
The variable hours of ancient Japanese clocks
In Japan, days and night were divided into an equal number of ‘temporal hours‘, six in total. The length of each temporal hour varied depending on the latitude and season. This method was also used in Europe to calculate canonical hours in monastic life, although it was based on two sequences of twelve hours. ‘Temporal hours’ are so called to distinguish them from ‘equinoctial hours‘, in which each hour has the same duration throughout the year, as on equinoctial days.
Additionally, each hour of the Japanese day was associated with a sign of the eastern zodiac. Starting at dawn, the six hours into which the daylight hours were divided were characterised as follows:
| Japanese Hour | Zodiac sign | Time of day |
| 6 | Hare | Dawn |
| 5 | Dragon | |
| 4 | Snake | |
| 9 | Horse | Midday |
| 8 | Ram | |
| 7 | Monkey |
And accordingly, for the hours of the night:
| Japanese hour | Zodiac sign | Time of day |
| 6 | Rooster | Sunset |
| 5 | Dog | |
| 4 | Boar | |
| 9 | Mouse | Midnight |
| 8 | Ox | |
| 7 | Tiger |
A single archetype is the origin of different types of clocks
Essentially, there are five types of ancient Japanese clock. The first type is the indoor clock, which is designed to be placed on the floor. These often have a square pyramid-shaped pedestal and are weighted. Then there are indoor clocks designed to sit on shelves, which are also weighted. Next are the tabletop clocks, which are spring-driven. Vertical wall clocks, also known as stick clocks, are spring-driven too. Finally, there are personal clocks that are worn tied to the waist and kept in precious cases called inro.
Although these models came in different shapes and sizes, they were all derived from the same prototype. They had a bell for the chime and, in rare cases, an additional feature, typically a calendar.
Some had a double foliot — two bar balance wheels — where one operated during the day and the other at night. This enabled different oscillation frequencies to be combined, adapted to the varying lengths of daylight and darkness. However, the most common types had a single regulator: either a foliot or a ring balance wheel.
The ingenuity of the ancient Japanese clockmakers
If time shown on the clock had to reflect the traditional Japanese concept of time throughout the year, the length of the hours had to vary in some way. This was achieved using a mechanical device that counted identical beats. The solution was unique.
Every fortnight, the clockmaker had to visit the owner of the clock to adjust the spacing of the hour markers on the dial. Rather than being fixed in position, as they are on our dials, the hours were engraved on tabs that could slide along the time band. This made it possible to move the tabs closer together or further apart, accounting for the varying lengths of the hours during the day.
In the spotlight of collectors
These clocks were crafted by traditional Japanese clockmakers for high-ranking patrons, so they are rare and highly prized, depending on their quality and condition. They are more commonly found at international auctions and are rarely seen on the Italian market, where they are sought after by not only clock collectors, but also Japanese art enthusiasts.
