"A Study about Noroshi or Houka - A passage from science to history"(summary)
Lecturer: Susumu Kato
At this lecture, we visited a Medieval castle in Mie Pref. : We investigated the ruins which seem to have served as a platform for making signal fire. And we compared it with the one built in Edo Period. We selected some material for making Noroshi (signal fire), for example dung of wolves, cedar, Japanese cypress,moxa, pine tree, KNO3, and sulfur. This information is, amongst others, based on documents in Bansen Shukai. We examined the smoke, made from those selected materials. A semi-quantitative assessment of data quality was performed in OPM (Open Path measurement method). It said that the density of this smoke was higher than the one made of broad‐leaved tree or kinds of normal plants.
Furthermore, we calculated topographic data with kashmir3d to make a perspective and visualized map. The base points for this calculation were the platforms for Noroshi in Iga and Matsuzaka. This map was plotted over a bird's-eye view map of Iga. As a result, we were able to mathematically confirm the existence of the network of noroshi in this area. Until now, this has been mentioned only in a few documents in the history of Iga-city or Ureshino-town.
Based on the visibility data analysis at the former meteorological station in Ueno, we reported that there is not so much difference in visibility between S12 and S22. It can be 5-7 km by median size, or - around 6 o'clock in the morning - sometimes even 0 km due to fog.
The wind direction/wind speed data (from 1961 until 2014) at the former meteorological station in Ueno has also been examined. It shows that most frequent wind direction in Iga area is W or NNE and most frequent wind speed is 2m/sec.
This research clarifies that it is conditionally difficult to make a grand signal fire in Iga area.