Technology and Culture

Research Notes M ED IEVAL M ASONS’ TOOLS. 11. COM PASSzyxwvutsrqponmlkjihgfe AND SQUARE L. R. SHELBY This second paper in a series of studies on medieval masons’ tools is concerned with the compass and square.1 That these tools were of particular significance in the work of medieval masons is indicated by their frequent use as symbols of the craft, as in the seal of the stone­ cutters of Strasbourg, the masons’ windows at Chartres, and the se­ pulchral monuments of several master masons.2 The choice of the com­ pass and square by the masons themselves suggests that a study of the form and use of these tools might produce some valuable insights into the work techniques of these men. Indeed, the underlying assumption of this paper is that, until the history of their tools is adequately de­ scribed, the achievements of medieval masons cannot be properly evalu­ ated from a technological point of view. One of the more striking features of medieval masons’ tools is their simplicity. This simplicity contrasts even with the tools available to builders in early modern times and, in some cases, in antiquity as well. Dr. Shelby, Assistant Professor of Medieval History at Southern Illinois Univer­ sity, is an authority on master masons of medieval England. 1 See L. R. Shelby, “Medieval Masons’ Tools: The l.evel and the Plumb Rule,” Technology and Culture, II (1961), 127-30. Recently my attention was drawn to a medieval text that corroborates the conclusion in this article regarding the use of the level. See the description of the level by the medieval mathematician, Leonardo of Pisa, in Scritti di Leonardo Pisano, matematico del secolo decimoterzo, II, La Practica geometriae, ed. B. Boncompagni (Rome, 1862), 108. 2See Pierre du Colombier, Les chantiers des cathédrales (Paris, 1953), Figs. 1, 7, 8, 12, 13, and 16, and Pl. XXVII. As late as 1545 the portrait of the master mason from Münster, Herman tom Ring, was painted with the left hand grasping a compass. See F. M. Feldhaus, Geschichte des technischen Zeichnens (2d ed.; Wilhelmshaven, 1959), Abb. 61. But the compass also symbolized other occupations. Albrecht Dürer used it in his engraving “Melencolia I” to represent the work of the mathematician (i.e., geometer: cf. E. Panofsky and F. Saxl, Dürers “Melencolia I” [Leipzig, 1923], pp. 66-67), while Agostino Romelli placed it in the frontispiece of his Le diverse et artificuose machine (Paris, 1588) to symbolize the engineer. 236 M edieval M asons'Toolszyxwvutsrqponmlkjihgfedcb 237 In order, therefore, to provide a basis for comparison and contrast, we shall glance briefly at the periods preceding and following the Middle Ages in this study of the medieval compass and square.3 Perhaps the earliest device used by the ancients to draw an accurate circle was the simple one made by attaching a string to a peg and rotating the radius formed by the loose end of the string.·1 This tech­ nique may have been used by the Egyptians, who do not seem to have possessed the compass.5 However, the compass was known to the Greeks; indeed, according to ancient legend it was invented by Perdix, nephew of Daedalus, the famous craftsman of archaic Greece.6 Three different words were applied by the Greeks to the instrument for draw­ ing circles: tornos, karkinos, and diabetes. Since these words were used but not defined by classical Greek authors, the precise character of the object referred to cannot easily be determined. Tornos is a word asso­ ciated with turning, or making round, and may refer only to the device of peg and cord for describing circles.7 On the other hand, both karki­ nos—which also means “crab” and “pincers”—and diabetes, associated with the idea of walking or stepping across, call up images of the com­ pass with legs for marking off circles.8 However, there is no need to elaborate here a philological discussion of these Greek words, for we 3 For developments in the construction and use of the compass and the square in more recent times, see W. F. Stanley, A Descriptive Treatise on Mathematical Drawing Instruments (5th ed.; London, 1878), pp. 21-58; W...