THE PARTHENON AND ITS SCULPTURES. 75 " The joints of the marble fit so closely that it is frequently difficult to perceive them, and it is almost impossible to imagine a finer line than they show. This can hardly have been pro- duced by other means than that of the stones having been rubbed upon one another." Penrose goes on to say, following an observation of Stuart's, that some of the stones had grown together : " May not the attraction of cohesion taking place between the two surfaces in almost absolute contact be sufficient to account for it ? " " Difficulty occurs in explaining how the vertical joints of the architrave could be brought to such exquisite fineness. Some light has been thrown on this ques- tion by an inscrip- tion reciting the method to be used for building a temple at Lebadea — ver- milion and olive oil were to be applied in some unexplained manner, and a stone canon, or rule, was to be used."* Choisy, commenting on this passage, observes that the method in question must have been that called by French masons "dressage au rouge," where the red powder, Jiaving been applied to a true plane, the newly wrought stone is brought in contact with it until it takes up the red equally all over, thus proving that it also has been brought to a plane. An inscription regarding the works at the Erechtheumf also mentions polishing a canon. Doubtless a true vertical was also set up by the side of the plane table so that perfect right angles could be obtained. n^ Fig. 6oA. — Diagram of Portico : after Choisy.
- Penrose.
+ Penrose, pp. 25 and 124.
