LAW & PRACTICE superv1s10n the roof was re-slated (the contractors had told the bursar that the coating could be cleaned off but - surprise surprise - this was impossible. He discovered that the 'cowboys' had coated not only the area of deteriorated slates but also an area which had been reslated only ten years earlier! This case is a classic example of the all-too-familiar principle that the British will go to any expense to get something Mike Pearce has some thoughts on appropriate units for measuring old buildings on the cheap. I hope I hardly need to point out the way in which limited failure (nail sickness) of the joints, and of a basically durable building material (the slates) was 'repaired' by using a short-life coating made it impossible to re-use the remaining sound slates with many more years' potential useful life. John Preston, Cambridge City Council 4a Rose Crescent, Cambridge. First stage of coating on the right, secondstage on the left. SPARETHE ROD More can be learnt about historic buildings, or their sites, if they are surveyed in the measure by which they were built, particularly now char the metric measure has replaced the Imperial measure in general use. If our prehistoric monuments are regarded as our earliest surviving buildings then, perhaps, one should make use of the megalithic yard which Professor Thom has calculated at 2.72 fr (0.829 m). Few Roman buildings remain standing, bur to understand their sires one could use the Roman foot of 11.6 inches (0.296 m). From documentary sources and sites in Winchester, R.D. Connor has equated the Saxon gyrd to the medieval rod at 16 fr 6 in (5.029 m). Four rods is a recurring module in the layout of new towns or extensions to them from the ninth to the 13th centuries. Variations were used, particularly in agriculture when a larger perch was used for measuring woodland. One wonders whether the measure may have extended to cut timber. A cord of wood today is 128 cubic feet, which is measured as a pile of logs 8 fr by 4 fr by 4 fr. A cord to measure it would be 16 fr long. It is tempting to wonder whether a unified system of measurement for land and buildings might have extended to growing and cutting the wood that was used. The rod was the measure of land bur cloth, the other principal source of wealth, was measured by the yard. The curious relationship of five and a half yards to the rod may have arisen as the land measures were already well established when the yard was defined as CONTEXT 40 36 inches in the 13th century. Before then it appears the rod may have been defined as the average of 16 feet, or 20 without shoes. An alternative measure of the foot could be made hand over hand with the thumbs extended, of which there would be approximately 16 to the rod. There is some evidence that the rod was often the basis for setting out medieval buildings, particularly timberframed buildings, bur the subdivisions are not clear. My own observations lead me to expect frame dimensions which will show whole, three-quarter or half rods horizontally and half rods vertically, usually measured overall the first or largest frame, and from there to overall each subsequent frame. Sometimes, however, particularly where there are masonry walls, the rod dimensions appear to be internal. Sections and joints may be dimensioned in inches, but a joist or rafter spacing of 16 inches, which is a modern measure, has earlier precedents which might be interpreted as a twelfth of a rod. Many medieval buildings, however, may nor have been set our in rods at all. A recent analysis of the design of Salisbury Cathedral published by the RCHM, for example, suggests numerically based proport10ns dimensioned in feet. No rod appears to have survived, which seems surprising. A length of wooden pole might be used in the field, but it would be rather unwieldy on a building site. Even a pair of half rods would be none too easy to handle. Standard yards were made in iron, but surely never a rod. If it were a cord of rope, it could nor have kept its length with the accuracy needed for carpentry. One would have expected a parish rod to have been kept. It would be nice if a pair of churchwardens' wands were to make a rod, but they seem too short unless someone knows of an older pair the right length. The Conservation Officers might be able to help: first by looking at medieval buildings with an eye to their rod measurements ro see if they may have been used for setting out, and whether some subdivision of the rod was used, or whether smaller dimensions were solely based on feet and inches (if the rod was used in medieval building, then when was it last used?); secondly, to find a rod, which even the Science Museum has not got. The finder will be rewarded. BIBLIOGRAPHY R.D. Connor: The Weightsand Measuresof England The Science Museum, London (HMSO, 1987) O.A. W. Di Ike: The Roman Land Surveyors: an introduction to the Agrimensores (David & Charles: Newton Abbot, 1971) P. Grierson: English linear Measures: an essay in origins. The Stencon Lecture, 1971 (University of Reading, 1972) P. Kidson: Salisbury Cathedral. Perspectives on the Architectural History. Part II The Historical Circumstances and the Principles of Design. Royal Commission on the Historical Monuments of England (HMSO, 1993) G.I. Meirion-Jones: A Fifteenth-century Stone Hall at Odiham, Hampshire, Archaeological journal, Vo! CXXVIII, The Royal Archaeological Institute, 1972 A. Thom: Megalithic Sites in Britain (Oxford, 1967) 33
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