The following outline summarizes the major architectural tools of the Jomon period through the results of an investigation of unearthed 4，000 year –old structural members and an experiment to restore them. (1) This architecture was characterized by high –raised–floors. (2) The structural members of this “high-raised –floor architecture ” were joined with mortises，tenons，and other specialties of joinery. (3) Chestnut trees were a commonly used architectural material. (4) The structural members of the time seemed to have been worked with stone axes and adzes of ground serpentine. (5) Large stone axes were the major tools used to fell timber. (6) Large stone axes， wooden wedges， and large stone adzes were the major tools used for lumbering. (7) Stone axes，adzes，and chisels were the main tools used to work structural members. (8) A large number of people were needed to frame a structure， the major components of which were enormous posts. (9) The latest restoration experiment clarified that， in the Jomon period， stone chisels played a major role in working structural members.

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The wooden handle of the historic Japanese adze fits into a socket，called a hitsu，in the iron adz head. We compared the different shapes of the iron adz heads which have rectangular hitsu，on the basis of this museum's collection of artifacts. We also interviewed extant blacksmiths in Yoita in Niigata Prefecture and in Miki in Hyogo Prefecture. These rare practitioners of a virtually extinct craft still make adzes using historic forging technology. In a comparison of adze shapes， we found that the wider and longer blades popular in the Tohoku region gave way to the narrower and longer blade as we moved westward. We also noted that ship carpenters generally preferred adzes with double–beveled working edges，while house carpenters seemed to have used both the double-and single beveled varieties. With regard to the adze forging technology， in both Yoita and Miki，the hitsu and the blade were forged separately，t hen joined together. In both regions，special anvils called karasuguchi were used to forge the hitsu; however， the blade forging techniques were different. Both techniques were improvements on ancient methods.

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