1992 Volume 101 Issue 7 Pages 1267-1295,1398-
For cocoon reeling, cocoons must be warmed in water to soften the natural gum with which the fibre is covered. In modern silk mills, boilers are used to make steam, and the water in the basin, in which the cocoons are placed, is kept at the proper temperature by means of the steam. In old Japan, a basin for cocoon reeling was warmed over an open fire, but it was difficult to keep the water in the basin at a uniform temperature. Also the thermal efficiency of this system was not good. In the early-Meiji era, the French cocoon reeling system was imported to the national silk mill at Tomioka, nearby Nagano pre-fecture. Some managers of indigenous silk mills and some enterprisers soon realized the necessity of boilers. Because the imported boiler was very expensive, they requested native casters and coppersmiths to make thems. These native makers made them by means of casting iron or rivetting sheet copper, according to the native Japanese technique, because the performance demanded of those boilers was not so high. These boilers costs less than one fifth of the imported ones. It was difficult to make larger ones, so in the 1880's, large silk mills purchased Western-style (mainly Cornish) boilers from makers in Tokyo and Yokohama. On the other hand, in 1879, a native coppersmith (MARUYAMA Yasaburo)developed the new boiler, which was made of imported thin (1/8 inch) iron plate. It was more efficient than cast iron, and the cost was not very different. Many medium and smaller scale silk mills used them. In the 1890's, makers in this area began to produce better boilers, which were combinations of the cornish and Multitubular boilers, and could serve as the largest boilers demanded in the area. At the same time, due to increasing demand, some skilled craftsmen came from Tokyo and Yokohama, opened iron works and entered the boiler making industry. The silk mills in this area could now buy any size of boiler, which cost about one fifth of those bought by silk mills in other districts. The above mentioned development of the boiler making industry was an important condition for the growth of cocoon reeling in Nagano prefecture and its environs.