<論説>木製楔の基礎的論考

Abstract

楔は一端を薄く尖らせた道具で、隙間に打ち込んで木を割ったり固定したりする機能をもつ。木器生産の製材工程に関わる工具でありながら、遺物としての認定が難しく、これまで主だった検討対象とならなかった。木材の利用法を具体的に解明するための手がかりとして、本稿は木製楔を題材とし、縄文時代から古代の資料を集成したのち三タイプに分類して時期ごとの様相を整理する。また楔で割り裂いた材の観察を行い、残された楔の痕跡をもとに製材技術を復原する。さらに樹種同定の結果を考慮して、楔の様相から背後にある木材資源との関連性を読み取っていく。材の樹種組成や用途に着目して、割材利用のあり方が特徴的な三遺跡の様相を整理し、それぞれ広葉樹分割材、同みかん割材、針葉樹を集中的に利用していたことを明らかにした。この三類型それぞれに、概ね三タイプの楔が対応することを示し、楔が木材利用に密接にかかわる道具であるとの位置づけを行った。さらに複数タイプの楔が併存する背景には、木材資源の複合的な利用があったとの結論を導いた。今後は、より包括的な木器生産論を展開するために、従来の未製品を主体とした検討とともに、原材の把握を通して木材の獲得工程から視野に入れ、木材利用論とも接点を持つ必要がある。

Before the introduction of the saw, boards could only made by using wooden wedges and mallets to split them off from logs. Even though the wedge occupies a significant position in Japanese history, no research has yet explored how precisely these pieces of wood were used. Based on 89 surviving samples from the early Jomon period through the ninth century, this monograph reveals how wedges were made, and explores their importance as a carpentry tools. Wedges can be divided into three types: rounded wedges, split-wood wedges, and board-like wedges. These wedges coexisted at the same time and were likewise created from various types of wood, with rounded wedges being made with either hard or soft wood, split-wood wedges made from hardwoods, and board-like wedges made from softwoods. One can evaluate the role and significance of wedges by exploring how they were used. Surviving boards contain vital clues, for marks that reveal how wedges were used to split them. From these boards, one can speculate that hardwoods were used to make tools and spades, and that softwoods were used for building. Split-wood wedges were used to split hardwoods, and to make plows and spades. The hardwood split-wedges of the middle Yayoi period were in all probability used to make spades and plows. Finally, board shaped wedges were used for splitting soft woods, so as to make boards for construction, or for strengthening wood structures made from these boards. To conclude, one gains greater insight into the material culture of the past by exploring both how ancient tools were used and created, and by paying attention to the woods that these objects were constructed from.