A smaller semi-circular section is removed from the board, so that the tool looks somewhat like a truncated horseshoe (Fig. A miniature from the early fourteenth century 10 represents this tool as a semicircular board with a diameter of probably less than a foot. More complicated and probably less accurate was the use of the plumb rule in checking vertical walls. This provided a decided advantage over the ancient tool in working with small stone, for the levelness of several stones could be checked simultaneously. But the medieval level, being a straight-edge, checked the levelness of the masonry along the entire length of the level. Because of its form, the ancient tool could check the levelness only of two points at a time, namely, those points at which the two legs of the level touched the course of masonry. An interesting com parison of the use of the ancient and the medieval levels may here be noted. This indicated that the stonework was not exactly level and that it needed adjustment. But if one end of the level was higher than the other, the plumb line and the vertical mark did not coincide. Shelby directly beneath the point at which the string was attached.9 When the level was placed on the top edge of a horizontal course of stone, the plumb bob hung free if the wall was level the plumb line hung directly over the vertical line drawn on the straight-edge. Shelby, a Graduate Teaching Fellow at the University of North Carolina, is engaged in research on the technology of medieval masonry construction. Though the details of the miniatures do not show it, there was probably a vertical line drawn on the side of the straight-edge, * Mr. We may now reconstruct the way in which the medieval level was used. 3).8 With these latter, the plumb line was attached to the vertex of the two legs and thus hung across the middle bar connecting the legs. 2).7 These levels contrast with the Egyptian and Roman levels, which were A-shaped (Fig. A fifteenth century miniature depicts a similar level, but with the semi circle replaced by a vertical board, from which hung the string and plumb bob (Fig. The string was of sufficient length so that the bob hung below the bottom edge of the level. From this semi-circle hung a string with a plumb bob attached. Medieval masons also used the principle of the plumb line, but the tools which they devised for its use were quite different in appearance and in application from those of the Egyptians and Romans.5 A thirteenth century miniature6 clearly portrays a level that was simply a long board, or straight-edge, with a raised semi circle in the middle of the top edge (Fig. The problems of leveling a horizontal course of stone and of plumb ing a vertical wall had been solved in ancient Egypt and in Rome with the use of various tools incorporating a line and weight, that is, a plumb line and bob. We may take as examples the form and use of the mason’s level and plumb rule. SHELBY* In contrast to the vast number of studies dealing with medieval art and architecture, the technology of medieval construction has received relatively little attention.1 Much work remains to be done in this field, particularly in studying the development of equipment and tools used in medieval construction work.2 Unfortunately, no medieval Virtruvius or Heron of Alexandria supplied detailed descriptions of equipment, tools, or methods of construction.3 In view of this absence of authoritative written sources, it is unfortunate that little use has been made of manuscript miniatures.4 Yet miniatures can be a valuable source for the history of medieval construction work, as is demon strated by the study of medieval masons’ tools. Research Notes MEDIEVAL MASONS’ TOOLS: THE LEVEL AND THE PLUMB RULE LONNIE R. In lieu of an abstract, here is a brief excerpt of the content:
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