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Some Problems for Mismatching of Transferred Western Technique in Traditional Water Mills of Japan


For application of European technique to the traditional water mills in Japan, several mismatching points are pointed out. The cause for those is attributed to the partial imitation of the equipment without the enough consideration about the mechanical system and traditional life style. From this result, we suggest several remarks for the acceptance of transferred technique. These points are important for applying many local technique to improve the environmental problem in the 21 century.

Key Words: Water Mill, Western technique, Transferred technique, Water Wheel, Traditional style

1. Introduction

After about 1900, traditional equipment and technique in Japanese home industry were changed partially or completely to European style[1] by employing transferred technique. Even in the traditional water mills for grinding rice and milling flour, European technique has been introduced on the mechanism, for example, for moving the pestle and also for rounding the mill for making flour[2]. The mechanism characteristic in Europe is however not always suitable for the purpose. To clarify it, we notice home water mills in Japan since the idea for the transferred technology by non-professional peoples can be reflected on it.
In this paper, we point out the mismatching points in home water mills, and clarify the cause for it. In Sec.2, we suggest characteristic features of water mills in Japan, based on several relationships between the size and materials of wheels. In Sec.3, we discuss general remarks about the acceptance of transferred technique, based on the results in Sec.2. It may give a useful hint for the acceptance of foreign technology, and be fruitful for the transfer of the local technology in 21 century for resolving the environmental problems.

2. Measurements and Results

The data about the size and rotational speed for water mills are taken partially from previous works[3], and also by direct measurements from 1985 to 1995 in Japan. The width and diameter of wheel are shown in Fig.1. The iron and wooden wheels are drawn by open and closed symbols, respectively. We classify the mills into three groups from the proportionality for the linear lines through the points, marked with the symbols A, B and C.
Three characteristic points changed by the transferring technique in water mills are presented. The first is the material of the wheel. It is traditionally wood but those of the transferred and European styles are iron. The iron wheel in Japan becomes popular after about 1950. We found about 50 iron and 40 wooden wheels. Others are the mixture of wood and iron. Typical types are shown in Fig.1.

Fig.1 Diameter versus width of water wheels. Traditional(Japanese), modified and European styles are shown by squares, stars and triangles, respectively, and also by the characters A, B and C, respectively.

The second is the shape of the wheel that is characterized by the ratio of diameter to the width as shown in Fig.1. The Japanese type A that is made by wood or iron has the large diameter but its width is narrow. The European type C has the considerable wide width. The modified type B is the intermediate between A and C, with no large diameter as shown in Fig.2.

Fig.2 (a) Traditional, (b) modified and (c) European styles of water wheels.

Concerning those types, we notice the rotation speed since it seems to be dependent on the kinds of the types and materials. We show the time for one rotation and the ratio of the diameter to the width, D/W (=R), for Japanese and transferred types in Fig.3.

Fig.3 Ratio of the diameter to the width of water wheel versus their speed for rotation.

For modified types, we find rather high rotation speed in comparison with that of Japanese type. The cause for this may be attributed to the smooth rotation arisen from the iron shaft and the wide width with small diameter, as seen in Fig.1. The cause for large scatter of measured points may be partly depend on the different strength of water stream for operating.
We further notice the material dependency of the speed. In Fig.3, iron and wood wheels show linear lines with different proportionality. The iron wheel seems to take high speed, and has rather large diameter. Since such wheel having a large diameter produces a large power, the iron wheel can move more number of pestles under high speed.
The third characteristic point is the mechanical system for transferring the rotation force from the wheel to the pestles. In the Japanese style, the power of water wheel is transferred directly from the shaft to the vertical pestle using the wing bar with the mechanism, as shown in Fig.4a. On the other hand, most of all modified type is made by varying the Japanese style, and small diameter of water wheel is employed, as seen in Fig.1. Then the position for the shaft of the wheel is lowered from the previous position, though the position of the shaft for the pestle is not varied. Then the force of the wheel is transferred indirectly by employing pulleys or gears as seen in Fig.4b. Pulley A takes a smaller radius than that of B, and then the rotation speed is lowered.
On the contrary, European types employ different mechanical system for the transffering the power of water wheel. Many pulleys with different diameter are inserted to one shaft and it is set at upper side of the room. Then each pulley moves a different kind of equipment with different rotation speed. This system is not disturbed by the positions of the wheel and equipment, as seen in Fig.4c, in which a water wheel is out side of wall at the left hand side.

Fig.4 Mechanical system of traditional(a), modified(b) and European(c) styles for moving pestle.

3. Discussions

3.1 Rotation speed of water wheel

In traditional method for grinding the rice, the falling pestle is employed under the gravitational force. Then the speed for the falling takes upper limit, and high rotation speed of the wheel is not needed. Because of this reason, the speed of water wheel in the modified type is too fast and therefore it must be corrected. The speed is decreased to match it to the pestle by employing the pulleys A and B with a belt, as shown in Fig.4b. From this result, the enhanced speed of the rotation due to the transferred technique seems to be mismatching to the Japanese tranditional method.
To match the rotation speed with the pestle, another method was employed, that is to take off a wing bar. For example, four wing bars are changed to the three. Then the speed is decreased to 3/4 of previous one.
For the cause for this mismatching, we attribute the formal imitation without enough understanding about the mechansm of the mechanical system. We further conclude that the direct import of the equipment and system is not appropriate for getting a better system for the grinding the rice.

3.2 Quality of products

We discuss the mismatching point with respect to the quality of the rice and rice flour. In the Japanese method for grinding the rice, the rice is hit by a pestle, and the ricebran is taken off. Then the speed for the hitting is limited as described in Sec.3.1, and the rice is not heated.
In the European machine, the grinding of rice is performed by inserting the unpolished rice between the iron nails. Although this method realizes the mass production by increasing the rotation speed of equipment, unpolished rice is heated because of the rubbing of it with the nails, and the taste of the rice is changed to no good in contrast to that of traditional style. From these results, high speed of water wheel is no meaning for obtaining the good quality of the rice. Requiring the mass production using the water wheel having the large diameter, Japanese style makes it possible by increasing the number of operating pestles, rather than the enhancement of rotaion speed of the wheel[3].

3.3 Mechanical system for producing flour

Even today, a millstone moved by water wheel is used in many local places of Japan. The purpose for the use is to obtain a good quality of the noodle flour. This result reveals that Japanese water mill is a valuable equipment for obtaining a good quality of flour.
To produce high quality flour, we find similar problems described in Sec.3.2. In the mechanical system for rotating the millstone, we find the characteristic difference in Japan and Europe.
In Japanese style, a millstone is rotated by the wooden gears touched with the upper stone at the out side, as shown in Fig.5a. On the other hand, in modified style, upper millstone is rounded by an iron bar inserted from the under part of the millstone at the center, as shown in Fig.5b. This type is mainly employed after 1945, and the style is almost the same with European type shown in Fig.6, though the diameter and the thick of the millstone in Japan are about a half of those in Europe.
For this type, we can rotate the millstone more rapidly, and then a large torque is needed. Therefore strong rotation force is required, and this is in contrast to that of the Japanese style since Japanese millstone is moved by a weak force with wooden gears having a large diameter, circumscribed with stonemill, shown in Fig.5a.

Fig.5 a) millstone and gear for traditional type, b) millstone moved by an iron bar in modified type.

Fig.6 a typical European millstone

3.4 Power of the wheel and pond as a reservoir

We notice another characteristic point about the mechanical system. It is the pond used for supplying constantly the water to the mill and makes it possible to operate the mill regularly under high rotation speed. Such a pond is very popular in Europe.
In Japan, such a pond however has not been employed, even in the home industry. Although we find many ponds in Chugoku and Shikoku districts, they are prepared for satisfying the water into the paddy field. Under no pond, the wheel with wide width is not appropriate since such a wheel is effective under much volume of water.
Now we indicate that the Japanese type of the wheel is appropriate for Japanese life style and also for the natural feature since a large diameter of the wheel that is the traditional style of Japan does not give so high speed but rather a large power, and the lots of pestles can be operated with no high speed. In standard type of home water mills in Japan, four or five pestles and one mill are set. To move these equipments, much power is not required, and therefore this condition for the use of the mill is sasifyed by a small stream. From this result, the water wheel with narrow width and large diameter is appropriate for grinding the rice, and the nature and traditional life style of Japan are also appropriate.
From these results described above, we suggest that we should understand the mechanical system of transferring equipment with respect to the traditional life of Japan, and consider the possibility for matching of the system with the traditional equipment. These remarks are useful for transfer of local technology that becomes active in 21 century since it does not destroy strongly the natural feature of land, and also not waste only a kind of energy source.

4. Conclusion

We found transferred technique introduced in home water mills in Japan. These are materials, the shape of the wheel and the mechanical system. The modified type of the wheel has small diameter and relatively wide width. The modified type was changed from the traditional type into new system that has pulleys and both the shafts for the pestles and the whell or with few number of wing bars. This revolution gives high speed on the wheel, but no good quality on the rice and the flour. In spite of active transferring of European technique, the pond was not employed because of the natural feature and also of the work of water mill, characteristic in Japan.
From these results, we indicated that the high rotation speed realized by the transferred technique does not always give a good result. For the simple application of European technique without enough consideration about the mechanical system and also about the traditional life and local features, we emphasize that the transferred technique should be employed under enough matching with the local technique, the local life, and the natural feature of the land.


  1. Many examples are written on "Papers on the history of industry and technology of Japan " Ed. by E.Pauer (Marburg, 1995, Marburg Univ).
  2. see for example, K. Kawakami, ibid., vol.II, p87 and K. Wakamura, ibid., p159.
  3. K.Wakamura and T.Shinohara, Bulltein of Okayama University of Science, 22 (1985)p.126.