As you may know, Miraikan is located in the area called Odaiba close to Tokyo Bay. I think Odaiba is a great place for entertainment, don’t you?
In fact, back in the 1800s, Odaiba was a defense fortification, where the Tokugawa government installed cannons to protect the Edo (now Tokyo) shore from American naval invasion.
News! The furnace that cast the cannons may be registered as the World Heritage in the near future.
It is called the Nirayama Reverberatory Furnace located in the northern part of Izu peninsula in Shizuoka prefecture. Just recently, the Japanese government nominated it as a part of the Modern Industrial Heritage in Kyushu and Yamaguchi to be included in the world heritage list in 2015.
Built in 1857, the Nirayama Reverberatory Furnace has two twin towers (16m x 5m each) facing at 90-degree angle. The exterior is made of stones, and the interior is fire-resistant bricks.
The reverberatory furnace was the place to smelt iron and make cannons. Because iron requires very high temperature to be melted, the furnace easily suffered heat damage and didn't last long. This is why there is no reverberatory furnace left in Europe where it originated in, but rather here in Japan! High-quality fire-resistant bricks used inside the furnace contributed to preserve the Nirayama Reverberatory Furnace in pretty good conditions.
The first step of making cannons is to get pig iron out of iron ore using a smelting furnace. Iron ore is a raw material rich in iron oxides. Redox reaction removes oxygen from iron ore. The product, pig iron, is hard but brittle, because of the carbon (~5% of weight) contained. To make iron hard and elastic enough for cannons, carbon needed to be removed.
The reverberatory furnace was necessary for the second step. During this process, the carbon contents was lessened down to ~1%. The unique mechanism is inside the furnace. Let’s take a look.
The dome-shaped ceiling inside the furnace reflects the heat from the fuel, and generates very high temperatures (~1200 degree Celsius). The furnace has a window to send air to the melting pig iron, so that the carbon in the pig iron combines with oxygen in the air. In that high-temp environment, carbon is carried away in the forms of carbon monoxide and carbon dioxide.
The melted iron was cast while it was still hot. This process wasn't possible without the waterwheel stand on the Narukawa River nearby.
Surprisingly, the iron pig was manufactured in Kamaishi in Iwate prefecture (far north from Izu peninsula!) and was shipped all the way to Izu for cannon casting. Then, the cannons as finished products were shipped again to Edo (Tokyo). What work! It tells how serious the government was to protect its own country with the best resources and knowledge possible.
Actually, the Nirayama Reverberatory Furnace wasn’t in Nirayama first, but in Shimoda, north coast of Izu peninsula, where Perry’s US Black Ships arrived. It was moved because the sailors broke into the reverberatory furnace site while in construction. Perry’s said at that time, “Industrial technologies in Japan will overtake those in America in 100 years.”
Proudly, Japan now has sophisticated technologies in iron manufacturing. It would be so nice if the historical sites (including Nirayama Reverbaratory Furnace) are registered as World Heritages, because as a driving force, they contributed so much to Japanese industrial development.
However, approximately 1000 world heritages exist already. I used to question, “Are all historical sites going to be world heritage sites?” But now I can loudly say the title “world heritage” has a huge, positive impact.
Because that is what linked Odaiba, my work place, and Nirayama, my hometown! I realized that I knew so little about my own hometown as well as Japanese history. What a fun and unique learning opportunity! I really want many people to have eye-opening experiences like this one I just enjoyed.
Lastly, time for an announcement!
This is going to be my last blog. A huge THANK YOU to all the readers! Though I will leave Miraikan soon, I continue to be a big Miraikan fan just like you! Wishing all of you a happy, healthy, and peaceful life♥