Abstract
In the last paper an experiment was carried out on each full-scale model of the domical vault in the case of Saint-Serge Church. And in this present paper the flat-ridge-like vault in the case of the Cologne Cathedral which was constructed by the method of the Amien Cathedral. As the specific gravity of Ohya Stone is relatively light and similar limestone, I formed the Ohya Stone into the size of the vault stone of Saint-Serge and Amien. We used mortar of the ratio of slaked lime: Sand: Water= 1: 4: 1 (ratio of weight) to lay stones. I come to the following conclusion as a result of this experiment: 1. Since both ends of the French stone layer of the flat-ridge-like vault are almost equal in height, the construction is less advantageous than the domical vault. But in the vault of the Cologne Cathedral, the bedding of the stone layer has the maximum horizontal angle of 70°. And so the vault can be built freehand by using a supplementary construction tool. 2. From the results of the experimental constructions of the domical vault and of the flat-ridge-like vault, I found that in the case of the flat-ridge-like vault the English stone layer is more advantageous in construction than the French stone layer since the former has more different hight on both ends of the stone layer. 3. In this experiment, I used three kinds of supplementary tool: Stone-rope, prop and cerce mobile. These simple supplementary construction tools are effective in freehand construction, but it is assumed that the other various skillful tools were used. 4. The freehand construction of a vault is generally considered to be a construction method of the East, such as the Orient or Byzantine architecture, but it was also a basic construction method for a vaulting in Western Europe in the middle ages.
