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National Science Museum and Toshiba Activate "Man-nen Dokei" Chronometer

8 March, 2005

Project recreates the masterpiece multi-functional chronometer
Created in 1851 by Hisashige Tanaka, Toshiba's founder

man-nen dokei

The National Science Museum
Toshiba Corporation

TOKYO -- Japan's National Science Museum and Toshiba Corporation today announced that they have solved a long standing mystery by reconstructing the "man-nen dokei," that literally means a clock that works for tens of thousands of years, the ornate, incredibly complex six-faced chronometer created by Hisashige Tanaka in the mid nineteenth century, Japan's Edo period. A team of researchers, engineers and specialists drawn from diverse fields, painstakingly disassembled the original chronometer, studied its intricate mechanisms, and crafted a working replica that will go on display at Expo 2005 in Aichi, Japan.

Tanaka, Toshiba's founder, was a prodigious inventor, known in his own lifetime as "the genius of mechanical wonders". His creations include the famed bow-shooting doll and the miniature alcohol-powered steamboat. But even measured against this rich heritage, the "man-nen dokei" stands out for its combination of sheer beauty and complexity.

Just 60 centimeters tall, and weight 38 kilograms, the chronometer has six faces, each of which presented the passage of time in a different way: a standard western clock; the phases of the moon; the oriental zodiac; Japan's ancient 24-phase division of the lunar year; the days of the week; and the passage of the day in the old Japanese way, dividing the hours of dark and light into six equal parts. The chronometer also chimed to mark the passing of each part of the day. Despite the extraordinary complexity of this design, the clock was reputedly designed to operate for a whole year on only a single winding.

The intricacy of Tanaka's masterpiece was complemented by its exquisite exterior: features that included a carved wooden base, cloisonne enameling, fine metal reliefs and delicate filigree work transformed a scientific marvel into a work of art, finished with the crowning glory of a representation of the orbits of the sun and the moon within a glass dome. All of these features have been recreated by modern craftsmen of Japanese traditional art, who confirmed the excellence of the original work.

The delicate structure of the original "man-nen dokei" has long made it an object of fascination, an interest stimulated by the silence of the original. The clock has been investigated before, but not in enough depth to unravel the secrets of its clockwork mechanism and how Tanaka integrated such complexity—or if it really could run for a year on a single winding.

Toshiba, the owner of the "man-nen dokei" agreed to work with the National Science Museum to investigate this mystery, and the project also won support from a Ministry of Education, Culture, Sports, Science and Technology national program to investigate inventions of the Edo age. In the course of a yearlong investigation, the research team carefully dismantled the chronometer, investigated its mechanisms, and successfully reproduced them. The study confirmed that the chronometer actually worked, and could do so for a year on one winding. Today, the replica of the clock was reactivated, when Mr. Tadashi Okamura, President and CEO of Toshiba, and Mr. Masamine Sasaki, Director General of National Science Museum together wound up the clockwork mechanism and ended 154 years of silence.

While today's Toshiba is a global entity, active in product areas as diverse as computers, semiconductors, social infrastructure and personal digital products, the company is still inspired by the inventive spirit of Hisahige Tanaka. As the company marks its 130th anniversary this year, participation in the "man-nen dokei" project once again brings home to Toshiba the importance of a passion for creativity, a driving desire to create exciting new products and systems that deliver "surprise and sensation" to customers around the world, and that add to the "safety and security" and "comfort" of people everywhere.

The original "man-nen dokei" is currently displayed in the National Science Museum. Members of the public will have an opportunity to see the Toshiba-owned replica from March 25 on, when it will go on display at EXPO 2005 Aichi, Japan. The clock will be featured at the Global House pavilion, managed by the Japan Association for the 2005 World Exposition, widely expected to be one of the Expo's main attractions.

The lessons learned from the deconstruction and reconstruction of the "man-nen dokei" will be revealed in due course, and will contribute to investigations of other aged artifacts.

Press Contacts:
The National Science Museum
Information Service Division
Tel: +81-3-5814-9851
Fax: +81-3-5814-9898

Toshiba Corporation
Corporate Communications Office
Tel: +81-3-3457-2105
Fax: +81-3-5444-9292

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