A wooden frame built especially to support the sides of an arch until the keystone is positioned.
A wooden frame built especially to support the sides of an arch until the keystone is positioned.
支拱板条专门用来在拱顶石放置好以前支撑拱的两边木架子
A wooden frame built especially to support the sides of an arch until the keystone is positioned.
支拱板条专门用来在拱顶石放置好以前支撑拱的两边木架子