Varieties of leaf tobacco in Japan can be broadly divided into various native species (300 and a few kinds at the time of 1901) that had spread to every region of Japan after they came down to Japan in the early Edo period and yellow species that the Meiji government transferred the technology from the United States aiming to make the domestic production of foreign-grown leaf tobacco in the late Meiji period. The demand of tobacco up to around the mid Taisho period was mainly native species, but the demand of lower-grade brand, yellow species, increased by recession, and the production area of yellow species, which was limited to Osaka and Hiroshima, began to gradually expand to the other Prefecture. Tobacco leaves produce unique taste and aroma by curing them. Although barns only to be used for curing tobacco seemed to be made by traditional construction method for both native species and yellow species in Japan, differences in their forms and structures and the use of the building were not yet cleared. Since the farmers who use a traditional tobacco curing room have almost disappeared and the demolition of the remains is increasing, the present study was made for the purpose of revealing the structure of the tobacco curing barn for yellow species.
It was found that there were "Osaka type" with hip roof and without soil ceiling, "Hiroshima type" with soil ceiling, and "eclectic type" with soil ceiling and hip roof by compromising both types, and eventually it was uniformly integrated in "Osaka-type" nationwide. For these 3 construction methods, most previous studies targeted the building of "Osaka-type", and the details of "Hiroshima type" and "eclectic type" which had been tried in the transition period were unknown. Therefore, in this study, we carried out the comprehensive survey of the remains including also "Hiroshima type" and "eclectic type”.
Since the curing barn of yellow species was built under the guidance of American engineer J. D. Jones in 1900, improvement was continued in order to make the more effective curing. The first curing barn was a building with a space of 3 Ken × 3.5 Ken, and the Japan's own standard of area: 2 Ken square, pillar length: 15 feet, have been established in the late Meiji period. Air warmed by the Kamado is circulated inside the iron pipe that was installed over the dirt floor of the barn to dry the leaves with its radiant heat. The temperature in the barn reaches up to 70 °C. The curing barn is wooden made and single-story. For curing, a minute-to-minute temperature adjustment table had been made under the guidance of the Monopoly Corporation, it was necessary to finely control the room temperature between 40 °C and 70 °C. For this reason, the building was required to have a structure with increased heat insulation property and airtightness as well as a performance to lower the room temperature by the rapid ventilation. The top window of the roof had been addressed for exhausting air and wet.
The features described above are common to the previously described 3 types, we describe below the difference in the structure of heat insulation and exhaust in the ceiling and barn construction. A Hiroshima type curing barn with soil ceiling had a gradient of 4 Sun (a Sun is roughly 30 mm), it had 4 sliding-type wooden doors at the top of the slope ceiling to open and close them in the barn back by riding on top of the soil ceiling. Exhaust was done from both sides of the roof gable surfaces of the opened roof.
