Nightingale floor, Uguisubari ( 鴬張り )

We have had the distinct pleasure of walking over the nightingale floor at Nijo Castle and in Toji-in temple both in Kyoto. Without previous warning we where even more surprised by the experience.
These are the places we know of that have a "nightingale floors" or in Japanese: Uguisubari:
  1. Daikaku-ji temple in Kyoto.
  2. Ninomura Palace in Nijo Castle in Kyoto.
  3. Chio-in temple in Kyoto.
  4. Toji-in temple in Kyoto.
The "nightingale floor" is made with a special timber technique from 17th century which makes it impossible to walk on the floor without it making quite beautiful squeaking sounds.
The idea of the floor surrounding the living and sleeping quarters of the palace was to work as alarm system. No one could enter the space without being heard.

A nightingale (refers to Japanese Bush Warbler, Uguisu) floor is designed specifically for security reasons. The floorboards of a hallway and the walkboards around a residence are designed to squeak as you walk across it. The nails for the floorboards pass through a metal clip. As you walk on them the floors chirp like a bird (thus the charming name) thereby alerting the residents of the adjacent room of your approach.
A welcome sound
To hear the birds sing
across the nightingale floor

From the Guide Map of Ninomaru Palace

From the entrance of the Ninomaru Palace to the Ohiroma (Grand Chambers), the wooden floors squeak and creak when ever anyone treads on them.
When the floor is tread upon, the cramps under it move up and down, creating friction between the nails and the cramps which hold them in place, causing the floor to squeak. It is the bird-like sound thus emitted that gives this, the name "Nightingale floor".
This is an information poster about the construction of the Nightingale floor that hangs on the wall in Ninomaru Palace.
At close look the construction is different from that drawn in our hand-out (above). However some of the construction details that unfold on photo's are also different. There may be more than one solution to this simple but ingenious mechanism.
What we show here is not the beauty of Nijo Castle, its buildings and gardens.
This page is limited to the principle and construction of the "Nightingale floor" as it exists today.
Nijo Castle was built in 1603 to be the official Kyoto residence of the first Tokugawa Shogun Ieyasu, and was completed in 1626 by the third Shogun Iemitsu.

The castle itself has two moats and two sets of walls. Once you get inside the first wall (look for the colorful Koy as you walk over the moat) you see Ninomaru Palace where court was held.

Here to show the walk boards a photo of the rear side.
Modifications were completed in 1626, but some of the original castle was destroyed over the years by fire. The main building is Ninomaru Palace that is open for visitors. Taking photos is not allowed inside. There is also a beautiful garden.

A close up of one of the Nightingale floors.

This floor is not vissually different from any floor that we have seen and walked on, without the sound mechanism.
The following photo's where taken underneat walkboard in Nijo Castle, Kyoto.

All the floors in the castle, from the entrance to Ohiroma, are this type of floor.

A close-up view underneath the floor. As you can see this this is different from the above construction diagrams.
An other view-angle on the same construction as above.

In the James Bond novel "You Only Live Twice" by Ian Fleming, a nightingale floor is mentioned.
...... the famous nightingale floor. Constructed with exquisite skill, it sings at the tread of each human foot. No assassin can cross it unheard.

And again a slightly different construction.

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