The earliest rice milling took is Mortar-pestle which emerged as early as the New Stone Age. (Neolithic Period) Later, processing tools such as pounding, flat milling, hulling, and polishing were developed. As mentioned earlier, rice milling is basically divided into two stages namely: “dehusking/dehulling”and“rice refining.”〔rice pounding 〕There are separate tools or equipments used in these two stages. This type of labor division was particularly apparent during early periods.
　
◆《Dehusking/dehulling tools-Stone husk separator stone husk separator, wooden grinder, soil grinder》
Basically, dehusking/dehulling tools are classified as to material into three types: stone husk separator, wooden grinder, and soil grinder. A stone husk separator is made of stone. Although it is durable, it is rather bulky. Moreover, stone materials are rarely found in Taiwan. A wooden grinder is made of wood. It is quite durable, and it dehusks/dehulls greater quantity of grain. However, this type of tool can only be used by strong men. As for the soil grinder, it is rimmed by bamboo clappers covered in sun-dried or heat dried clay. It is apparently not durable in nature. As a matter of fact, the dehusking/dehulling quantity is much less as compared to wooden grinders. However, it is easy to use even for women and children. Also, bamboos are grown abundantly in Taiwan, thus, soil grinders are the most commonly seen dehusking/dehulling tools. It is for this reason, places where dehusking/dehulling are carried out are otherwise known as “soil grinding rooms.”
Stone husk separator, wooden grinder and soil grinder all work under the same principle. A huller is divided into upper and lower polishing discs. The contact points of the two discs should possess grooves.〔toothlike structures〕These grooves are used to polish rice grains. Grooves of stone husk separators and wooden grinders may be directly engraved and bored on, but the interior material of the soil grinder is soil, thus, the wooden or bamboo strips may be shredded into small pieces and inserted in the upper and lower discs. This way, the two contact points become toothlike convex or concave structures that grind the rice hulls.

A soil grinder in display in the Science and Technology Museum	The interior of a soil grinder is  made up of dried clay
Plywood is inserted in the groove to grind grain	We visitation to the Science and  Technology Museum

◆《Rice refining tool-stepping grinding, water mortar》
A tool used to refine rice is called “Tui (rice pounding)” including stepping, Gang-tui [manpower], Tsao-tui, water mortar, Lian-Ji-Tui [hydraulic〕stepping, and Gang-tui. (Lever principle) Brown rice is first placed inside a stone mortar. A person steps on the wooden Tui to pound rice. Rice bran and broken rice are then sieved to obtain milled rice /polished rice.
Since manpower stepping was energy consuming, hydraulic rice pounding subsequently emerged. Water troughs are setup at the pedal, the weight of the water allows the“Tui”to move in up and down motion which is otherwise called “Tsao-tui.” River water then moves the mill wheel to turn the wheel axle. The movement of the Tui lever is called “water mortar.” Later, Du Yu invented Lian-Ji Tui in which the water mortar wheel axle increased in length to become several sets of water mortars. The rice pounding speed increased as a result.
Since water mortars need hydraulic power and are limited by the environment, they are less commonly used. During the olden times in Taiwan, rice pounding mainly depended on mortar-pestle or stepping. Water mortar use was rare.
　

Stepping display at Science and  Technology Museum	Water mortar display at Science and  Technology Museum