Ashlar construction in galicia in the baroque period. The tracings in the tribune of the chapel of saint telmo in tui

Construction in hewn stone requires the use of geometrical means in order to control both the general layout of the built member and the shape of the individual masonry elements. Fullsize tracings have been used with this purpose since Classical Antiquity. In this paper, we shall describe and analyse a not-so-well-known example of these tracings, in the chapel of Saint Telmo in Tuy, which are connected with the façade of the chapel. We have carried out a survey of the ensemble of the tracings by means of rectified photographs; at the same time, we have prepared a survey of the most significant elements in the façade, using a laser total station, in order to compare the tracings with the built chapel. All this has allowed us to gather valuable first-hand information about the formal control methods used in Baroque construction that treatises and manuscripts cannot furnish directly.