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years ago in Japan daylight and nighttime were each given 12 hours and clocks were made to adhere to this ... throughout the year as summer days grew longer and nighttime shorter their clocks adjusted to make an hour longer or shorter self adjusting

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TIL - this is very cool. It looks like somebody actually put together a wari-koma (temporal) watch in 2011 as well.

https://www.masahirokikuno.jp/watches/temporal-hour-watch/

If you want to look at some old ones the Seiko museum in Tokyo has a few. Entry is free and I can only recommend it.

Thanks for the tip! The wadokei clocks on the museum's site look incredible.

https://museum.seiko.co.jp/en/collections/traditional_Japane...

The non-fixed type system per https://ja.wikipedia.org/wiki/%E5%92%8C%E6%99%82%E8%A8%88 was called "futei jihou" (non-fixed time system), same with other sites https://museum.seiko.co.jp/knowledge/relation_16/ . "Temporal hour system" seems like the correct translation.

My guess is that "wari koma" here means basically "separated panels" (wari: broken, koma: panel). Wadokei means (traditional) Japanese timepiece.

Just double checking, but the day and night were each given 6 hours, not 12.

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