Japanese clock - Wadokei

Mechanical clocks made in Japan during the Edo period. Based on mechanical clocks introduced from the West, clockmakers invented and modified them during the isolationist period to fit the time system and lifestyle of Japan at the time, making them unique to Japan. Mechanical clocks were introduced to Japan in 1551 (Tenbun 20), when missionary Francis Xavier presented a clock to Ouchi Yoshitaka, the feudal lord of Yamaguchi, when he asked for permission to evangelize. As Christianity spread, more and more clocks were brought to Japan. Meanwhile, the missionaries spread the manufacturing method, and during the Keicho period (1596-1615), the technique was passed down from Kyushu to the Kinki region. Tsuda Sukezaemon, said to be the father of Japanese clockmakers, repaired a self-ringing bell (clock) owned by Tokugawa Ieyasu, made a clock based on it, and presented it to him. He later served as a clockmaker to the Owari Tokugawa family. After the Shimabara Rebellion, the completion of the isolationist policy (1639) meant that clocks were also cut off from exchange with Europe. Unlike Western countries, which moved toward adopting a fixed time system (a method of dividing a day and night equally) due to the invention of mechanical clocks, Japan focused on creating clocks that were compatible with the Japanese time system, which was based on sunrise and sunset and in which the length of a moment changed during the day and night and every day. The production of Japanese clocks was rare in the early Edo period, but by the middle of the Edo period, the number of clockmakers employed by feudal lords increased and the industry gradually flourished. In 1796 (Kansei 8), Hosokawa Yorinao wrote a book on clock manufacturing called Karakurizui. The word clock that we use today also dates back to the Edo period, but in the past it was written as tokei, tokei, dokei, jimei-sho, and jishin-gi. With the reform of the calendar and the adoption of the fixed time system in January 1873 (Meiji 6), Japanese clocks lost their practical use, and many were discarded, with some exported overseas. In addition, the Japanese clock industry, which was a craft product, disappeared because it was no longer competitive with foreign products.

Japanese clocks are classified as follows based on their shape and mechanical structure.

(1) Tower clock The mechanism is placed on a fire tower-shaped stand and is powered by a weight lowered into the stand. At first, there was only one foliot balance, but to eliminate the need to move the weight attached to the arm of the balance to adjust the length of an hour during the day and night, a mechanism was devised that had two balances, one for daytime and one for nighttime, and automatically switched between six o'clock in the evening and six o'clock in the morning (two balances). The time is indicated by the zodiac and the number of the hour, and there are various methods of displaying the hour, including those with moving hands and those with fixed hands facing upwards and a rotating dial. A divided piece dial was also used, in which the length of an hour was adjusted by moving a small piece (warikoma) on which the time was written to widen or narrow the gap. A similar type to the tower clock is the table clock, which is mounted on a four-legged base and is the oldest form of wall clock.

(2) Shaku-dokei (Japanese square clock): The mechanism is housed in the top of a long, narrow box, and a weight lowers to operate the mechanism. A pointer is attached to the weight, which moves over a time scale attached to the front of the box to show the time. Dials are made using one of three types: a split-piece dial, a knotted board type in which a board with a different scale is replaced for each season, or a corrugated board type in which time scales for each season of the year are engraved. This is a unique style of clock not found overseas, and is hung on a pillar.

(3) Pillow Clocks: These are table clocks powered by a spring, decorated with beautiful carvings and gold plating, and housed in cases made of rosewood, ebony, etc.; they are more than just clocks; many of them are luxurious and intricate and are used as decorations.

In addition to the above, there are also gravity clocks, table clocks, paperweight clocks, pocket watches, inro clocks, etc. The perpetual clock made by Tanaka Hisashige in 1851 (Kaei 4) at the end of the Edo period is a type of astronomical clock and is famous as the greatest masterpiece of Japanese clocks. It is currently preserved at the National Museum of Nature and Science in Ueno, Tokyo.

[Kuniyuki Motomochi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

江戸時代に日本でつくられた機械時計。西洋から伝来した機械時計を基に、鎖国の状況下で時計師たちが、当時の日本の時刻制度、生活様式にあうように考案、改造した日本独特の時計である。日本への機械時計の伝来は1551年（天文20）、宣教師フランシスコ・ザビエルが山口の領主大内義隆(よしたか)に布教の許可を願い出た際、時計を献上したことに始まる。その後キリスト教の広がりにつれ時計の持ち込みも多くなった。一方、宣教師たちによってその製造法が伝えられ、慶長(けいちょう)年間（1596～1615）には九州からやがて近畿地方においても伝習されるようになった。日本の時計技術者の祖といわれる津田助左衛門は徳川家康所有の自鳴鐘(じめいしょう)（時計）を修理し、それを見本に時計一台をつくって献上し、のち尾張(おわり)徳川家に時計師として仕えた。島原の乱後、鎖国の完成（1639）によって時計もまたヨーロッパとの交流を断たれ、機械時計の発明によって定時法（一昼夜を等分する方法）の採用に向かった西洋諸国とは異なり、日の出、日の入りを基準とし、一時(いっとき)の長さが昼夜、そして毎日変化する日本の時刻制度にあうような時計の実現に力を注ぐことになった。和時計の製作は江戸時代初期にはまれであったが、中期になると大名のお抱え時計師の数も増え、しだいに盛んとなった。1796年（寛政8）には時計の製造について『機巧図彙(からくりずい)』という著述が細川頼直(よりなお)によって書かれている。現在使用している時計の語も江戸時代からであるが、古くは斗景、斗鶏、土圭、自鳴鐘、時辰儀(じしんぎ)などと書かれた。1873年（明治6）1月の改暦と定時法の採用によって和時計は実用性を失い、その多くは廃棄され、一部は海外に流出した。また工芸品的な和時計産業は外国との競争力をもたず消滅した。

　和時計は形状や機械の構造によって次のように分類される。

（1）櫓(やぐら)時計　機械部は火の見櫓状の台の上に置かれ、台の中に下げられた重錘(じゅうすい)を動力として動く。棒てんぷは初め一つ（一挺(いっちょう)）であったが、昼夜の一時(いっとき)の長さを調整するためてんぷの腕にかけられている分銅の位置を移し変える手間を省くため、昼間用と夜間用のてんぷ二つを備え、暮六つ、明(あけ)六つに自動的に切り替わる機構（二挺てんぷ）が考案された。時刻は十二支および刻の呼び数で示され、その表示方法には針が動くもの、針が上向きに固定され文字板が回るものがあり、また一刻の長短を時刻を記した小片（割駒(わりこま)）を動かして間を広げたり狭めたりして調整する割駒式文字板も用いられた。櫓時計と同種のものに四脚の台にのせた台時計、形式としてはいちばん古い掛け時計がある。

（2）尺時計　細長い箱の上部に機械部が納まり重錘が下がって機械を動かす。重錘には指針がつき、箱の前面に取り付けられた時刻目盛りの上を移動して時刻を示す。割駒式、季節ごとに目盛りを変えた板を取り替える節板式、および1年間の各季節の時刻目盛りを刻んだ波板式のいずれかの文字板が用いられている。外国にはみられない独特の形式の時計で柱に掛けて、用いられる。

（3）枕(まくら)時計　ぜんまいを動力とした置き時計で、美しい彫刻や金被覆で飾られ、紫檀(したん)、黒檀などのケースに入れられ、単なる時計にとどまらず、装飾としても利用される豪華で精巧なものが多い。

　和時計には以上のほかに重力時計、卓上時計、卦算(けさん)（文鎮）時計、懐中時計、印籠(いんろう)時計などがある。江戸末期の1851年（嘉永4）田中久重(ひさしげ)の製作した万年時計は一種の天文時計で和時計最大の傑作として名高く、現在東京・上野の国立科学博物館に保存されている。

［元持邦之］

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