Time is not measured the same way everywhere.In Japan, before adopting the Western time system, watchmakers devised mechanisms adapted to the rhythms of nature, clothing customs, and traditional representations of the universe. From the small watch hung on the kimono belt to complex astronomical clocks, these creations reflect a technical culture where function, ornamentation, and thought converge.

A watch reflecting a way of life

In Japan, the encounter with European mechanical watchmaking in the 16th century gradually opened a new chapter in the history of time. Imported mechanisms were studied, adapted, and transformed to meet local uses. From this appropriation arose a specific watchmaking tradition known aswadokei.

Unlike European clocks, generally designed to measure hours of constant duration, traditional Japanese clocks had to accommodate a seasonal time system. Before the 1872-1873 reform, day and night were each divided into six units whose length varied according to the seasons. Time was thus closely linked to the solar cycle and natural conditions.

This particular conception of time is reflected in the diversity of objects developed by Japanese artisans: weight clocks, table clocks, column clocks, and portable watches. The Paul-Dupuy Museum in Toulouse notably documents this adaptation of mechanical clockmaking to Japanese uses.

Among these creations is the inro-dokei, a watch designed from a traditional everyday object: the inrō.

The inro-dokei: measuring time worn at the waist

The inrōis a small compartmentalized case, traditionally used to carry personal items, notably medicines. Worn at the kimono's waist, it is suspended by a cord and held by a netsuke, a small carved element serving as a counterweight.

Japanese watchmakers adopted the shape of this accessory to incorporate a watch mechanism. By removing the inner compartments of the case, they created an object capable of housing a movement while maintaining the principle of an accessory suspended at the waist.

The inro-dokei thus differs from European pocket watches by its format and its relationship to clothing. It is not simply about miniaturizing a clock, but about integrating it into a system of objects and gestures unique to Japanese culture.

Its casing can be decorated with plant motifs, landscapes, or finely crafted compositions. The watch then becomes an object with a dual function: a timekeeping instrument and a piece of decorative craftsmanship.

Some specimens also show technical exchanges between Europe and Japan. Movements from European pocket watches were sometimes reused in Japanese cases, illustrating a practice of adaptation rather than mere imitation.

The inro-dokei thus embodies a form of creativity where watchmaking expertise meets decorative arts and daily uses.

Hisashige Tanaka: when watchmaking meets astronomy

On another scale, this same adaptability is evident in the work of Hisashige Tanaka (1799-1881), a Japanese inventor and engineer from the late Edo period and early Meiji era.

Known asKarakuri Giemon, Tanaka first made a name for himself with his mechanical automata, capable of performing complex movements. His interest in mechanisms, mathematics, and astronomical knowledge then led him to design highly sophisticated clocks.

In 1850, he completed the Shumisengi, an astronomical clock that embodies a Buddhist representation of the universe. Its name refers to Mount Sumeru, a cosmic mountain central to certain Buddhist cosmologies.

At the heart of the instrument, a depiction of the mountain is surrounded by devices representing the movements of the Sun and the Moon. The whole reflects a geocentric conception of the cosmos: the celestial bodies revolve around an earthly center symbolized by the mountain.

This creation is therefore not solely about measuring time. It gives mechanical form to a worldview. The movement of the parts makes a cosmological order visible, while the clock becomes the material support of a philosophical and religious representation.

The Seiko Museum Ginza presents the Shumisengi as one of Tanaka's major achievements and highlights the connection between his watchmaking work, his astronomical knowledge, and Buddhist cosmology.

The Man-nen Jimeisho : a mechanism in the rhythm of the universe

Tanaka's ambition continues with the Man-nen Jimeisho, also known as Man-nen-dokei or “thousand-year clock.” Completed in 1851, this piece is now preserved at the National Museum of Nature and Science in Tokyo.

About 57 centimeters tall, it combines six dials with complementary functions. These allow, in particular, the display of traditional Japanese time, Western time, days of the week, dates, and various calendar markers. Its upper part features an astronomical device representing the movements of celestial bodies.

The clock demonstrates remarkable mechanical mastery. Its system must notably account for seasonal variations in the length of hours in the traditional Japanese calendar. The combination of several displays also reveals a desire to make different time measurement systems coexist.

Its aesthetics fully contribute to its uniqueness. Lacquer, mother-of-pearl inlays, and metal decorations transform the instrument into a work of art, without separating beauty from technical complexity.

The Man-nen Jimeishothus constitutes a major testimony to Tanaka's ingenuity and the richness of Japanese watchmaking on the eve of the profound transformations of the Meiji era. It is now recognized as an important cultural property of Japan.


Two ways to make time visible

Theinro-dokei and Tanaka's astronomical clocks serve different purposes. The former places the measurement of time within the personal and clothing universe of its owner; the latter translate, through complex mechanisms, a broader conception of cosmic order.

Their comparison nevertheless reveals the same approach: watchmaking that is not limited to indicating the time. In one case, the mechanism is integrated into a daily object charged with aesthetic value. In the other, it becomes a mechanical representation of celestial cycles and the calendar.

These creations also testify to a period of transition. Japanese watchmakers assimilated technologies from Europe while adapting them to their own uses, traditions, and systems of thought. In 1873, the adoption of the Western hourly system at constant intervals marked the end of the official use of the old seasonal system.

But this transformation does not erase the originality of the Japanese technical heritage.

From finely decorated portable watches to the astronomical clocks of Hisashige Tanaka, these objects remind us that the history of watchmaking is also that of the societies that shape it. Measuring time is always about choosing a way to inhabit it, organize it, and give it meaning.

Sources and references

Museum and heritage sources

  1. Paul-Dupuy Museum, Toulouse — Clocks at the time of the Rising Sun. Presentation of traditional Japanese clocks, the seasonal time system, and theinro-dokei.
    https://museepauldupuy.toulouse.fr/horlogerie/la-collection-dhorlogerie/pendules-a-lheure-du-soleil-levant/
  2. Seiko Museum Ginza — Shumisengi. Note dedicated to the astronomical clock by Hisashige Tanaka, completed in 1850.
    https://museum.seiko.co.jp/en/collections/traditional_Japanese_clock/collect009/
  3. Seiko Museum Ginza — Hisashige Tanaka (1799–1881). Presentation of the inventor and his work in watchmaking and astronomy.
    https://museum.seiko.co.jp/en/knowledge/inventors_04/
  4. National Museum of Nature and Science, Tokyo, via Google Arts & Culture — The Myriad-Year Clock. Presentation of the 1851 clock, its dials, and its astronomical devices.
    https://artsandculture.google.com/asset/the-myriad-year-clock/twFlv5fVX7bjeg
  5. Japan Society of Mechanical Engineers — Mechanical Engineering Heritage No. 22: Man-nen Jimeisho. Heritage notice dedicated to the design, mechanism, and functions of the clock.
    https://www.jsme.or.jp/kikaiisan/heritage_022_en.html
  6. Japan Clock & Watch Association — History of timepiecesHistorical landmarks on the development of Japanese watchmaking and the transition to the Western time system.
    https://www.jcwa.or.jp/en/etc/history.html

Additional documentary source

  1. Documentary excerpts provided for the preparation of this article, dedicated to the portable watchinro-dokeiand the astronomical clockShumisengi, especially in figures 25 and 27.The Watch Library