Official

So far, I've covered topics related to Shinkawa, such as the Seven Wonders of Rei Kishijima, the ruins of Echizen moat, and Oiwa Inari Tamiya Shrine.
However, it is no exaggeration to say that there are not many visitors in this area for sightseeing.
Did you know that Shinkawa is a very important place when talking about surveying?

When you go near Chuo-ohashi Bridge, you will notice that there are traces of the Reigishijima tide station and water mark, which are often introduced on the Chuo-ku correspondent blog.
Since it is also published in the official text of the Chuo-ku Tourism Test, "Chuo-ku Monoshiri Encyclopedia", isn't it relatively familiar?

The identity of the water mark that you are worried about is equipment to measure the water level of the river by measuring!
In the early Meiji era, when modern surveying in Japan began, water markings were installed in major rivers such as the Tone River, Sumida River, and Arakawa, and altitude was required based on the average water level obtained there.
And when the national unification of average water level data was carried out due to advances in surveying technology, the water level station on Rei Kishijima was chosen as the basis.
The altitude of the Japanese standard in Nagatacho, which was introduced in a previous article, was determined based on the data here. (Data revision was made after the Great Kanto Earthquake.)

Reishi Island water level station, which created such a Japanese standard, has now retired from the role of verification of the standard field due to the reclamation of Tokyo Bay and the river water of the Sumida River.

However, since then, we have continued to observe basic data for different purposes.
The Reishi Island water level station, which is currently seen, has been relocated about 36 meters downstream from the time following the enforcement of the Sumida River Terrace revetment, and symbol pillars have been installed at the original location to convey the historical history of observatory to future generations.
(The scale at the lower right is part of water level station.)

Immediately next to the place where Japan's altitude was the standard, something important for surveying is also installed unintentionally.
Yes, that's the first-class level, "King No.

This benchmark was relocated more than 10 years ago, but it has historically been very important as a starting point for Japan's height.
It's a very interesting place to have such a point!

Knowing the history of surveying in this way, do you not care where and how other benchmarks are installed?

When I walked with care of my feet as a trial, this was the first thing that came into my eyes.
This identity, which looks like a manhole and differs, is the Tokyo Metropolitan Standard Base used by Tokyo Metropolitan Government to conduct ground deformation surveys in Tokyo.
I often do not notice, but there are about 20 places in Chuo-ku.

In addition to the Tokyo Metropolitan Standard Base, there are three Standard Bases managed by the Geographical Survey Institute in Chuo-ku in addition to the first standard score "Koshin".
The locations are Tsukiji, Nihonbashibakurocho (top image), and Nihonbashihamacho.
I wonder if what the government manages is more strictly protected as a starting point for important surveying, and I am a little surprised because it is usually on the street.

This is installed at Tsukiji Temple.
Like Nihonbashibakurocho, it is designed with a map of Japan and a surveyor, and it is engraved with the Geographical Survey Institute of the Ministry of Construction, so you know that it is exceptional.
At the same time, I can imagine how long it was installed at least from the name "Ministry of Construction", and I feel the history again.

On the other hand, the standard base in Nihonbashihamacho has a slightly different design, and a large map of Japan is drawn.
These are used in public surveying standards, land subsidence, earthquakes, volcanic activity monitoring of plate tectonic, and public works projects such as road and water and sewage construction.

The standard base is not a place for sightseeing, but when you actually look for it, you can enjoy the fun as if you are searching for treasure on the city.
There are so many things that can be found right away, and those that cannot be found no matter how many times you look for them.
It may be installed evenly throughout Chuo-ku, and if you look for these and walk around the town, you will be able to go around the entire city!

If you think that the shape and altitude of Japan, which is now known for granted, have been revealed by the steady efforts of our predecessors, you can learn again how important each of these casual points have played an important role.

In Kamejima-cho, Hatchobori, Tadataka Ino, who created the map of Japan after conducting a nationwide survey for the first time in Japan, has set up residence.
Considering that, Chuo-ku may actually be a ward that has a deep relationship with surveying.
When you can go out freely, I would like to visit historical sites and spots related to surveying again.