Abstract
This paper describes an experimental free-hand reconstruction of the domical vault of Saint-Serge et Saint-Bacchus, c. 1215-c. 1225. References to both domes and vaults that were constructed without formwork or centering can be seen from time to time. M. de Lassaux, architect to the king of Prussia, is the discover and restorer of this process. He described how to erect such structures almost entirely free-handedly in the Journal of the Royal Institution of Great Britain in 1831. Somewhat later, Porter claimed that the early Lombard vaults were build 'virtually without centering' in 1911. On the other hand, Viollet-le-Duc, an authority on Gothic theory, held to theory of cerce-mobil (i.e. Centering) construction and this opinion seems to be dominant in the academic world. Mr. Kishiro lida, professor of Nagoya University, has claimed that the cerce-mobile is only a guide line for construction, and that the cerce-mobile construction itself is actually the same as the free-hand construction. I made this experimental study under the guidance of Mr. Lida. Conditions of experimentation 1. Utilizing a full scale model of the domical vault of St. Serge (Picture 1) 2. Use of mortar mixed at the rate of 4 parts river sand to one part slaked lime on the commercial market). 3. Use of Ohya stone (density 1. 5, length 31. 2Xheight 26. 8X width 15. 3 cm) as the material for the vault, conclusion 1. The adhensive power of the mortar of slaked lime is sufficient within a few minutes to construct the vault by free-hand method until the bedding inclination of stones comes to 60 degrees. 2. We can construct the vault all the way to the top by using the illustrated stone-weighted-rope method. 3. It is advantageous to free-hand construction that the courses of the stone arches are laid as at St. Serge. 4. The stone-weighted-rope method is useful in free-hand construction for high level work, and would seem to be used at the same time with the cerce-mobile.
