yorkshire archaeological journal, Vol. 86, 2014, 106–23 Viking-Age Lead Weights from Cottam Dave Haldenby Volunteer, Hull and East Riding Museum Jane Kershaw Institute of Archaeology, University College London This paper introduces a new dataset of Viking-Age lead weights, found over the last three decades at Cottam on the Yorkshire Wolds. The weights generate new insights into contemporary lead weight forms, functions, and weight standards. We compare the Cottam weights with other lead weights from contemporary sites in Britain, Ireland and Scandinavia, and suggest that they belong to a Scandinavian lead weight tradition. We also review the possible functions of lead weights, and suggest that the Cottam finds were scale weights, intended for use with hand-held balances, most likely for the weighing of staple commodities in exchange. The results of metrological analysis imply that the weights were manufactured in accordance with established Scandinavian weight units, specifically with an øre (ounce) of c. 24g. In this way, the paper contributes important new evidence for the existence and use of Scandinavian weighing systems in Viking-Age England. keywords lead weights, weight standards, Cottam, exchange, trade The purpose of this article is to draw attention to a group of hitherto unpublished lead weights, found over the last three decades at Cottam on the Yorkshire Wolds. The assemblage of fifteen well-preserved weights can be narrowly dated on the basis of associated finds to the late ninth and early tenth century. It represents a highly significant dataset for the Late Saxon and Viking period and generates new insights into contemporary lead weight forms, functions, and weight standards. Alongside the presentation of this material, we integrate evidence for lead weights from Viking-Age contexts across Ireland, England and Scandinavia, providing a wider context for the Cottam assemblage. We argue on the basis of the weights’ appearance and weight that they belong to a Scandinavian lead scale-weight tradition, and were produced in line with established Scandinavian weight standards, most likely for use within an economic context. These observations cast fresh light on the use and availability of Scandinavian weight standards in Viking-Age England, whilst at the same time signalling the importance of weight-based transactions at the late ninth and tenth-century settlement of Cottam. © The Yorkshire Archaeological Society 2014 DOI 10.1179/0084427614Z.00000000046 VIKING-AGE LEAD WEIGHTS FROM COTTAM 107 Cottam B Before moving on to the discussion of the lead weights, we first discuss the site of their discovery: Cottam B. The site now known as Cottam B is situated high on the chalk uplands of the Yorkshire Wolds, between Driffield and Malton (Fig. 1). Evidence for settlement in the Anglian and Anglo-Scandinavian periods has been detailed in a number of papers (Haldenby 1990; 1992; 1994; Richards 1999; 2001; 2003; Haldenby and Richards 2009). A combination of detector survey, field walking and excavation has revealed two clusters of finds associated with adjacent but distinct settlement foci, approximately 200m apart: to the south, an eighth/ ninth-century Anglian settlement and, to the north, a ninth/tenth-century Anglo-Scandinavian farmstead with a substantial gated entrance. Ninth-century finds, including pins, strap-ends and Northumbrian stycas, have been found across both areas, suggesting contemporaneous activity at both sites for several decades, whereas later ninth- and tenth-century material has been found only in the north. In the final excavation report, only the southern area was termed ‘Cottam B’, with the northern area being referred to as ‘north of Cottam B’ (Richards 1999). Here, as in other subsequent figure 1 The location of Cottam. 108 DAVE HALDENBY and JANE KERSHAW research papers concerning the site, the name Cottam B is used to describe both occupation areas of the site in question. (Cottam A is a different, Middle Saxon site lying approximately 1 km along a trackway towards the southeast). The two settlement zones of Cottam B are characterised by distinct finds assemblages. This pattern allows the close dating of different forms of long-lived artefact types, including some varieties of pins and strap-ends. It further provides important, independent dating evidence for the material discussed here, all of which is centred upon the northern farmstead with gated entrance (Haldenby and Richards 2009, 311). In addition to the weights, surveys in this area have yielded a number of late ninth- to tenth-century finds, including: an Arabic dirham minted in 928/29 (discussed below); York and Torksey ware pottery sherds; Norwegian ragstone hones; four tenthcentury strap-ends; three so-called ‘Norse’ bells; an early tenth-century Jellinge-style disc brooch; a late ninth or early tenth-century Borre-style buckle and certain varieties of ‘collared’ pins dated to the late ninth century, including plate headed forms with ring and dot decoration (Richards 1999, 94; Haldenby 2012, 7). Due to the tight chronology of the recovered artefacts associated with the Anglo-Scandinavian farmstead, it has been proposed that this was occupied only for a brief period of time, for around fifty years (Richards 1999, 97). The lead weights To date, fifteen well-preserved lead weights have been recovered from Cottam B, only one of which has previously been published (erroneously, as a finger ring) (Fig. 2) (Haldenby 1992, 35).1 The weights were found dispersed across the northern settlement zone and are thus unlikely to derive from a single set (Richards 2003, 160–2).2 Nevertheless, they have a homogenous character. All are regular and well made, with a mid-white patina. They comprise a number of different forms: seven weights are rectangular or square prisms, six weights are cylindrical, one is a truncated cone and one is ring-shaped. Although plain, a few weights also show signs of decorative or other markings. A large rectangular prism carries striations along its eight longest edges, for instance, while a cylindrical example has two sub-circular punchmarks on one face (Fig. 2, bottom row right, and bottom row left). Contextualising Viking-Age lead weights Plain lead weights are difficult to date on typological grounds, but the narrow chronological window of activity at Cottam B makes it highly likely that the weights belong to the late ninth or early tenth century. To what cultural context(s) do they belong? A review of the evidence for lead weights of similar date from England, Ireland and 1 2 In the final excavation report, several perforated lead items recovered from Cottam B were erroneously published as weights; however these had previously been correctly identified as spindle whorls. Richards 1999, 10; Haldenby 1990; 1992 Eight of the weights, found in the 1980s, were not individually plotted since they were not initially recognised as weights. A further seven weights have subsequently been found and plotted in light of the growing realisation that they are indeed weights. Their exact find spots are not being published, to guard against unauthorised detecting. VIKING-AGE LEAD WEIGHTS FROM COTTAM 109 figure 2 Lead weights from Cottam. From top left: weights 1–2 and 4–15 (no. 3 is not illustrated). Scandinavia, reveals some interesting trends. Notably, few contemporary sites in southern England have yielded comparable material (Kruse 1992, 79, 84). Four large, thick disc-shaped lead weights, some sheathed in copper-alloy, were found at Winchester and are believed to be Late Saxon in date, but they are of a very different form to the lead weights discussed here (Biddle 1990, 910–15 and 918, 280, nos. 3192 and 3195). A number of lead weights from the Vintry site in the City of London share features with the Cottam weights, but these are unfortunately impossible to assign to specific chronological periods (Drinkall and Stevenson 1996). In eastern regions, individual finds of disc-shaped lead weights are recorded from Late Saxon contexts at Thetford (Norfolk) and St Neot’s (Cambs), while three potential weights dated to the Late Saxon period are recorded from Ipswich (Suffolk) (Kruse 1992, 79). A possible lead weight was also recovered from the fill of a Late Saxon or Norman grave from St John’s cemetery, Norwich (Norfolk) (Huddle 2009). In England, the site with the largest quantity of lead weights dated to the ninth or tenth century is Coppergate, York. The Coppergate weights encompass cylindrical, spherical, truncated conical, and disc-shaped forms, and thus mirror the typological diversity of the lead weights from Cottam. They belong to Anglo-Scandinavian levels: 4B and 5A, dated by the excavators to 930/5–c. 975 and c. 975 respectively, although it is generally acknowledged that problems of object displacement and redeposition in later contexts characterised the Anglo-Scandinavian phases at the site (Mainman and Rogers 2000, 2456, Tab. 223, 2461, 2561–2, fig. 1259). In addition to York, the site of Flixborough, Lincolnshire, has also yielded several plain lead weights of comparable form, dated from the late ninth century (Wastling 2009, 422–23, fig. 13.3). 110 DAVE HALDENBY and JANE KERSHAW Flixborough was occupied throughout the Middle and Late Anglo-Saxon periods and has a complex occupational sequence, but the weights have been interpreted as reflecting Scandinavian influence and, possibly, the existence of a metal-weight economy (ibid., 422; Loveluck 2007, 120). The Anglo-Scandinavian context of the lead weights from York and, potentially, Flixborough, is of interest, since other sites with Scandinavian associations in Britain and Ireland have also yielded parallels for the Cottam weight assemblage. Solid, plain lead weights in the form of cubes, rectangular prisms, cones, pyramids and cylinders are recorded alongside decorated lead and copper-alloy weights of well known Viking type from the Viking winter camp sites of Torksey (Lincolnshire) and ‘A Riverine Site near York’, both of which are thought to have been temporarily occupied by the Danish ‘great army’ in the 870s (Blackburn 2011, 240; Hall and Williams forthcoming). The multi-period site of Llanbedrgoch, Angelsey, has also yielded finds indicative of ninth- and tenth-century Scandinavian contact or activity, including coins, weights and hack-silver. Among its weight assemblage are seventeen plain lead weights: some are square, others conical, and others in the shape of discs and truncated spheres (Redknap 2009, 38–9, fig. 4.7). An extensive collection of lead weights is also recorded from Viking-Age Ireland (Wallace 2013). The predominantly ninthcentury settlement of Woodstown (Co. Waterford) has been identified as a Viking longphort base. It has yielded thirty-one pieces of Viking-Age hack-silver, in addition to 200 lead weights. The tenth- and eleventh-century Dublin town excavations have yielded over 175 lead weights, including examples in flattened square, disc and bun-shaped forms (ibid.). Over seventy lead weights were dredged from the River Blackwater (Co. Armagh) along with Scandinavian silver and Insular metalwork and offcuts. This assemblage has been interpreted as the ‘stock-in-trade’ of a HibernoViking metal-worker or merchant, and may represent the spoil of a Viking raid on the nearby Armagh monastery in 895 (Bourke 2010, 26, 33, 126–7, Pls. 4–5, 128–9, Table 1; Wallace 2013, 311–12). Plain lead weights of comparable form and size are also recorded from other Scandinavian contexts in Britain. Two possible lead weights were found along with a set of scales in a tenth-century burial of Scandinavian character from Kildale, North Yorkshire (Redmond 2007, 113, and Appendix 6, no. 33). Culturally Scandinavian burials from Scar, Orkney, and Kiloran Bay, Colonsay, have likewise yielded plain lead weights, the latter in combination with a set of scales and a group of other lead weights with inset ornamental metalwork (Graham-Campbell and Batey 1998, 139–40, 119–20, fig. 7.4). Excavations from Dumbarton Rock in the Scottish Lowlands recovered a Viking-Age sword-hilt fragment and a decorated lead weight, in addition to a plain lead weight, which may also belong to the same period (ibid., 98–99, fig. 6.4). Turning to the Scandinavian homelands, we find even closer parallels for the Cottam material. Plain lead weights in diverse geometric forms constitute a prominent part of Viking-Age assemblages from settlements, including from central-place sites. Over 330 lead weights, including plain types, types with punchmarks and other markings, and types decorated with metalwork offcuts, are known from Kaupang, Norway. They are dated by stratigraphy from the second quarter of the ninth century and continued in use into the tenth (Pedersen 2008). Large numbers of lead VIKING-AGE LEAD WEIGHTS FROM COTTAM 111 weights also characterise other Viking-Age urban sites, including Hedeby (SchleswigHolstein), Birka (Sweden), Uppåkra (Sweden) and Ribe (Denmark) (Gustin 2004, 94–5; Hårdh 2010, 290; Feveile and Jensen 2006, 143, Pl. 5; the comments regarding Hedeby are based on Kershaw’s own analysis of the extant material). Smaller numbers are recorded from magnate farms, such as Gamle Hviding, Tissø and Lejre (all in Denmark) (observations based on Kershaw’s own analysis of the relevant finds; see too Jensen 1990; Jørgensen 2003, 181, 203). Given these parallels, and the scarcity of comparable material from contemporary Anglo-Saxon sites, a Scandinavian cultural background for the lead weights from Cottam seems highly likely. The lead weights, then, add to the existing evidence for a distinct strand of Scandinavian material culture at the site, as likewise seen in the Arabic silver dirham, Borre-style buckle, Jellinge-style disc brooch and, less certainly, the ‘Norse’ bells. Variability in form The forms exhibited by the Cottam B weights fit neatly within the spectrum of lead weight forms recorded within Viking-period assemblages, from both sides of the North Sea (Wallace 1987, 212; Redknap 2000, fig. 82; Pedersen 2008, 121–3; Eriksen et al. 2009, fig. 8.4).3 What was the purpose of such variability in form? In addition to characterising assemblages from settlement sites, typological variability is also a feature of plain lead weights contained in discrete sets, such as the eight variously shaped weights deposited in a Viking-Age grave from Sævli, Norway (Pedersen 2008, 127, fig. 6.9). Diversity within individually owned weight sets suggests that this feature served an important role in visual recognition, allowing the owners of weights to easily recognise their set in an environment in which multiple sets were in use, such as a trading transaction involving two or more merchants. Such ease of recognition was essential for guarding against fraud, and helped to avoid confusion introduced by traders working to different weight standards (see below). Other physical markings, such as simple punchmarks, or deliberate gouges and scratches such as appear on the Cottam weights, are also a feature of lead weights found in Viking-Age contexts in Scandinavia (ibid., 150–55). They may be interpreted as serving a similar function, although Unn Pedersen has suggested that, in some instances, punchmarks may also relate to the use of a particular weight unit (ibid.). Weight standards: a background The existence of weight standards in Late Anglo-Saxon and Viking-Age material has been the subject of intense debate by scholars in Britain, Ireland, and Scandinavia (for instance, Kruse 1988, 85–9; Pedersen 2008, 140–4; Kilger 2008; Wallace 2013; Hall and Williams forthcoming). A postulated Anglo-Saxon weight unit of 3.1 g, representing one tenth of a Troy ounce, was suggested by Smith in 1923 (Smith 1923). It occurs frequently in academic literature, but is extremely problematic, in part because there is no evidence for the existence of a Troy pound before the thirteenth century (for 3 The ring-shaped weight is unusual, but it does have parallels: in a lead piece from the magnate farm of Gamle Hviding, Jutland, as well as among the lead weights from Dorestad and Viking Dublin. Cf. Jensen 1990, 31, fig. 7, x377; Willemsen 2009, 123, fig. 148, bottom left; Wallace 1987, 212. 112 DAVE HALDENBY and JANE KERSHAW further problems in identifying Late Anglo-Saxon weight units, and further references, see Kruse 1992, 86, note 193). A number of variations on a Viking ‘ounce’ of c. 24–26 g have been proposed, both in weights and weight-adjusted silver objects such as arm-rings and ingots. Based on his study of lead weights found in Norwegian Viking-Age graves, A. W. Brøgger proposed a light ounce or øre, of 24.59 g, divided into three units, or ertogs, of 8.19 g (Brøgger 1921). He saw this ounce as replacing a heavier ‘old Norwegian’ ounce of 26.5 g, a standard which is, in turn, close to a unit of 26.6 g observed in lead weights from Viking Dublin (Wallace 1987, 206–7). In her study of the lead weights from Kaupang, Norway, Unn Pedersen found evidence for the use of a weight unit based on Brøgger’s light ounce of 24.59 g, particularly its sub-unit, an ertog, of c. 8 g (Pedersen 2008, 144). The lead weights from the Viking winter camp sites of Torksey and ‘A Riverine Site Near York’, are awaiting full metrological analysis, but Mark Redknap’s analysis of the seventeen plain lead weights from the settlement at Llanbedrgoch, Angelsey, suggests the possible use of a standard based on the Dublin unit of 26.6 g (Redknap 2009, 38, fig. 4.7). Conversely, Patrick Wallace has argued that the c. 200 lead weights from Woodstown, Ireland, reflect a ‘lighter’ unit of c. 22–23 g, which he sees as a Scandinavian introduction of the ninth century (Wallace 2013, 309, 313). Preliminary analysis of the plain lead weights from the River Blackwater (Co. Armagh), found evidence for both the ‘heavier’ (Dublin) and ‘lighter’ (Woodstown) units (Bourke 2010, 26). Metrology of the Cottam weights The extent to which it is possible to recover metrologically significant information from surviving lead weights is difficult to gauge. Lead weights are often corroded, meaning that their original weight is difficult, if not impossible, to reconstruct (Kruse 1988, 287). The use of weights in metrological analysis also assumes that they were originally manufactured to precise standards, and thus ignores the possibility that precision in weight units may not have been aimed for, or that some weights may have been inaccurate (and may have even been discarded for this reason). Some weights may not have functioned as such, but may have held symbolic value only, in which case their weight would not be expected to conform to established standards. Another possibility is that lead weights were calibrated differently across sites and time periods, and may thus vary in weight even within a system in which there was an agreed weight unit (McNamara 2005, 128; Pedersen 2008, 146). Nevertheless, the recovery of fifteen well-preserved lead weights with analogies in Scandinavian lead weight assemblages provides a unique opportunity to advance understanding of contemporary weight standards, and, in particular, to test for the presence of known Scandinavian weight units. We mapped the weights of the fifteen weights from Cottam against both the proposed Scandinavian weight units. For completeness, we also tested the weights against the proposed Anglo-Saxon unit (3.1 g), although we note that evidence for its contemporary use is essentially non-existent but for its repeated discussion in the literature. The dataset from Cottam B is, admittedly, limited. Nonetheless, the weight distribution of the fifteen weights implies the real existence of standards, specifically one based on Brøgger’s light øre of 24.59 g, divided into halves (half-øre) and thirds (ertogs). Weights range from 8.42 to 94.89 g (Table 1). They are fairly evenly distributed across this range, with pairs of weights clustering at c. 8, 12, 20, 24, 32 and 48 g VIKING-AGE LEAD WEIGHTS FROM COTTAM 113 TABLE 1 THE LEAD WEIGHTS FROM COTTAM, MEASURED AGAINST A UNIT OF 24.59G Actual weight Unit (øre/ ertog) Theoretical weight Deviation 8.42 g 1/3 øre (1 ertog) 8.19 g 0.23 g + 8.88 g 1/3 øre (1 ertog) 8.19 g 0.69+ 11.88 g 1/2 øre 12.29 g 0.41 g- 12.80 g 1/2 øre 12.29 g 0.51 g + 16.59 g 2/3 øre (2 ertog) 16.38 g 0.21 g + 19.47 g 1/3 + 1/2 øre 20.49 g 1.02 g - 20.74 g 1/3 + 1/2 øre 20.49 g 0.25 g + 24.65 g 1 øre 24.59 g 0.06 g + 26.02 g 1 øre 24.59 g 1.43 g + 32.48 g 1 1/3 øre 32.78 g 0.3g - 32.94 g 1 1/3 øre 32.78 g 0.16 g + 46.3 g 2 øre 49.18 g 2.88 g - 48.32 g 2 øre 49.18 g 0.86 g - 72.94 g 3 øre 73.77 g 0.83 g - 94.89 g 4 øre 98.36 g 3.47 g - (Fig. 3). This pairing is an interesting trend, and may suggest the existence of two weight sets. The heavier weights (24 g and above) show close correlations with one, two, three and four multiples of an øre of c. 24 g, while the lighter weights respect the half-øre (c. 12 g) and ertog (c. 8 g), and multiples thereof. A heavier weight standard of 26.6 g was also applied to the weights but found not to fit as well (Table 2).4 Table 1 reveals that the deviation from the proposed target weights is very small: under 1 g, in most cases. At 26.02 g, weight number nine is 1.43 g heavier than its suggested target weight of one øre. Interestingly, this weight is very close to the c. 26.6 g unit observed among lead weights from Viking Dublin (Wallace 1987, 206– 7). It also falls within the target weight range of 26.15 g ± 0.9 g identified in complete, weight-adjusted Hiberno-Scandinavian broad-band arm-rings, also believed to be Dublin products, and it may thus relate to a distinct, Hiberno-Norse weight system (Sheehan 2009, 67; but see Kruse 1988, 293). Among the heavier weights, numbers twelve and fifteen deviate from the 2 and 4 øre mark by -2.88 g and -3.47 g respectively. As a fraction of the overall weight of the weights, this scale of deviation is comparable to that recorded in the lighter weights. Nonetheless, this does suggest an increased error rate for heavier weights, raising the possibility that greater imprecision in weight standards was tolerated in larger transactions. Weights of c. 4 g and multiples thereof (e.g. 8, 12, 16, 20) appear frequently in Scandinavia, leading to the suggestion that this half-ertog, coined þveiti by Kilger, 4 In order to aid comparisons with the lighter ore unit, we have calculated units of halves and thirds, although it should be noted that Brøgger viewed the heavier as divisible only by sevenths. Brøgger 1921, 8, 16. 114 DAVE HALDENBY and JANE KERSHAW figure 3 Recorded weights of the lead weights from Cottam. TABLE 2 THE LEAD WEIGHTS FROM COTTAM, MEASURED AGAINST A UNIT OF 26.5G Actual weight Unit (øre/ ertog) Theoretical weight Deviation 8.42 g 1/3 øre (1 ertog) 8.86 g 0.44 g - 8.88 g 1/3 øre (1 ertog) 8.86 g 0.02 g + 11.88 g 1/2 øre 12.80 g 16.59 g 13.3 g 1.42 g - 1/2 øre 13.3 g 0.5 g - 2/3 øre (2 ertog) 17.72 g 1.13 g - 19.47 g 1/3 + 1/2 øre 22.16 g 2.69 g - 20.74 g 1/3 + 1/2 øre 22.16 g 1.42 g - 24.65 g 1 øre 26.6 g 1.95 g - 26.02 g 1 øre 26.6 g 0.58 g - 32.48 g 1 1/3 øre 35.46 g 2.98 g - 32.94 g 1 1/3 øre 35.46 g 2.52 g - 46.3 g 2 øre 53.2 g 6.9 g - 48.32 g 2 øre 53.2 g 4.88 g - 72.94 g 2 2/3 øre 70.92 g 2.02 g + 94.89 g 3 1/2 øre 93.1 g 1.79 g + was the principal weight unit, rather than the larger ertog or øre (Kilger 2008, 316; Pedersen 2008, 145). Weights of c. 4 g have not been found at Cottam B, but the coupling of weights at 8, 12, 16, 20 and 24 g may represent multiples of a core unit of 4 g, rather than 8 g or 24 g. This would explain the presence of two weights around VIKING-AGE LEAD WEIGHTS FROM COTTAM 115 both the 12 g and 20 g mark, and we may note that a base unit of c. 4 g (precisely 4.1 g) correlates well with the Cottam weights (see Table 3, below). That said, the remaining weights fit equally well with the ertog, half øre and øre. Of course, the ertog and þveiti are closely related, with the same common denominator. The proposed target weights could equally represent multiples of ertog, þveiti and øre (e.g. 12 = ½ øre or 1 ertog + 1 þveiti). The lead weights from Cottam B are at the heavier end of the spectrum recorded for lead weights of Scandinavian type, although they are broadly commensurate with the range of the seventeen lead weights from Llanbedrgoch, Angelsey (Pedersen 2008, fig. 6.19; Eriksen et al. 2009, 130; McNamara 2005, 127; Redknap 2009, fig. 4.7). It is unclear why lighter lead weights have not been found at Cottam B. It is unlikely to be due to detector bias. The light copper-alloy weights known as cubo-octahedrals (weighing c. 0.75–4 g) are similarly absent, despite the fact that several pinheads of comparable form and size have been recovered. It is possible that the prevalence of heavier lead weights reflects the particular contexts of use of the weights at Cottam B. However, the corpus of lead weights from the site remains small: lighter weights may come to light in future. A further step in the metrological analysis is to compare the proposed Scandinavian øre standards with the hypothetical Anglo-Saxon unit of 3.1 g. Table 3 correlates the weights from Cottam B with the 3.1 g unit, as well as with the proposed base units of the lighter and heavier øre: 4.098 g (reflecting a weight unit of 24.59 g) and 4.43 g (reflecting a weight unit of 26.6 g). The results show that the unit of 4.098 g TABLE 3 THE WEIGHTS FROM COTTAM, CORRELATED AGAINST THREE DIFFERENT BASE UNITS Weight x base unit 8.42 g 3/ 2/ 2 1.51– 0.22+ 0.44– 8.88 g 3/ 2/ 2 0.5– 0.68+ 0.02+ 11.88 g 4/ 3/ 3 0.52– 0.42– 1.41– 12.80 g 4/ 3/ 3 0.4+ 0.5+ 0.49– 16.59 g 5/ 4/ 4 1.09+ 0.19+ 1.13– 19.47 g 6/ 5/ 4 0.87+ 1.03– 1.75– 20.74 g 7/ 5/ 5 0.96– 0.24+ 1.41– 24.65 g 8/ 6/ 6 0.15– 0.05+ 1.93– 26.02 g 9/ 6/ 6 1.88– 1.42+ 0.56– 32.48 g 10/ 8/ 7 1.48+ 0.32– 1.47+ 32.94 g 11/ 8/ 7 1.16– 0.14+ 1.93+ 46.3 g 15/ 11/ 10 0.2– 1.2+ 2+ 48.32 g 16/ 12/ 11 1.28– 0.88– 0.41+ 72.94 g 24/ 18/ 16 1.46– 0.86– 2.06+ 94.89 g 31/ 23/ 21 Average deviation 3.1 unit 4.1 unit 4.43 unit 1.21– 0.59+ 1.86+ 0.98 g 0.58 g 1.26 g 116 DAVE HALDENBY and JANE KERSHAW (4.1 g) represents the best fit with the Cottam weights, with an average deviation of 0.58 g, compared to 0.98 g for the 3.1 g unit and 1.26 g for the 4.43 g unit. However, it is important to note that the maximum deviation for the 3.1 g unit is 1.55 g (half of the unit), while it is 2.05 g for the 4.1 g unit and 2.21 g for the 4.43 g unit: that 4.1 g has a lower deviation is thus notable, since (all else equal) we might expect the error associated with the 3.1 g unit to be the smallest. In order to compare the different weight units on an equal footing, we therefore need to scale the size of the deviation, or error rate, appropriately, and to express the deviation as a proportion of the weight standard. These proportional errors are shown for two model scenarios and each of the three units in Figs 4 and 5 respectively. To aid the interpretation of these figures, it is useful to consider Fig. 4. Histogram A is what we would expect of ‘perfect’, highly accurate weights that are exactly consistent with our hypothesized weight standard: the weights are a close multiple of the hypothesized standard unit, and thus their imprecision is negligible. Histogram B shows the error rate of weights not from the hypothesized standard: since they are not designed to correspond to the hypothesized unit, their weight is equally likely to fall anywhere between successive multiples of a basic unit, and thus their error rate is broad (uniform). Returning to Fig. 5, we can see that the error rate for the 3.1 g and 4.43 g units is more akin to the latter histogram: a significant proportion of the weights show a large error rate. By contrast, the error rate for the 4.1 g unit shows a different pattern: over half of weights have a marginal error rate (<10 per cent), displaying a pattern more akin to model histogram A. It is reassuring to see, now that the weight standards are on an even footing, that 4.1 g remains the best supported standard. figure 4 Model histograms, showing the error rate of highly accurate weights (A) and weights not from the hypothesized weight standard (B). VIKING-AGE LEAD WEIGHTS FROM COTTAM 117 figure 5 Histograms showing the proportional error rates of the Cottam weights, using three distinct weight standards. To summarise the results of the metrological analysis, we found no evidence for the postulated Anglo-Saxon unit of 3.1 g. Instead, the results suggest the real use at Cottam B of a Scandinavian weight unit based on sub-units and multiples of a light øre of 24.59 g, with the evidence of one of the weights (number nine) potentially indicating the co-existence of the heavier, ‘Dublin’ øre of 26.6 g. In this way, the weights appear to provide fresh evidence for the use in Viking-Age England of a Scandinavian weight system, which, one could speculate, is most likely to have been introduced in the wake of the Scandinavian settlements in the late ninth century. The analysis also highlights particular features of the weight unit system, suggesting, for instance, that less precision was required in weighing larger payloads compared to smaller sums. Given this background, we can now turn to consider the function of the lead weights, and their implications for our understanding of the character of the site at Cottam. Function and interpretation Comparisons with similar assemblages from both Britain and Scandinavia suggests that the lead weights from Cottam B are most likely to be scale weights, intended for use with beam balances. Lead weights are recorded in combination with balances and/ or scale pans from both settlements and graves within Scandinavia and from Scandinavian contexts in Britain and Ireland, including the burials at Kildale and Kiloran Bay (Jondell 1974; Wallace 1987, 214; Graham-Campbell and Batey 1998, 92, 119–20, fig. 7.4; Redmond 2007, 113, cat. no. 33; Pedersen 2008, 126–7; Griffiths 2010, 98, 113, fig. 67, 128). Two beams from folding balances have also been recorded from 118 DAVE HALDENBY and JANE KERSHAW figure 6 Fragment of a balance-beam arm, with stamped ring-dots. Cottam B: one, in the southern area of the site, comprising a single beam with inlaid silver studs, and a second, from the northern zone, comprising a central section and beam, ornamented with stamped rings (Fig. 6) (Haldenby 1994, 55, fig. 3 no. 6; PAS ‘Find-ID’ FAKL-CC0BE6). Both types carry distinctive rope-mouldings at the end of the arms, and find parallels among the corpus of Viking-Age balances from Scandinavia (for instance, Jondell 1974, 39, no. 5). The weighing capacity of folding balances of the type represented by the Cottam finds is difficult to gauge. A similar balance was found in a grave at Sævli, Norway, together with a number of lead weights, the heaviest of which weighed 53 g (Pedersen 2008, 143; Jondell 1974, 47, no. 22, fig. 35). Most of the lead weights recovered from the site could therefore probably be weighed using balances of the type represented by the beam fragments, although experimental results suggest that greater accuracy was achieved by weighing lighter loads (for a discussion, see Pedersen 2008, 138–9). The context(s) in which the lead scale weights were used is unclear. Due to their diverse form, there has been a tendency to assume that lead weights were employed exclusively in metalcasting (for instance, Steuer et al. 2002, 137). In some cases, lead weights have indeed been found in apparent workshops. At Birka, Sweden, for instance, mainly cylindrical lead weights were found in association with moulds and crucibles on the floors of metalcasting workshops dated c. 750–860 (Gustin 2004, 94–5, 311). Plain lead weights have also been found in association with workshops and casting waste at Ribe and Gamle Hviding, Denmark (Feveile and Jensen 2006, 144; Jensen 1990, 31). Such associations have encouraged the view that lead weights were used to measure out the correct quantity of metal alloys prior to casting (Steuer et al. 2002, 137) but other interpretations are possible. The evidence may simply point to the local production of lead weights. Alternatively, lead weights may have been required for the production of weight-adjusted objects, such as ingots, arm-rings, and other weights (Pedersen 2008, 167). This scenario would explain both the precision with which lead weights adhered to known weight standards and their physical association with workshops. VIKING-AGE LEAD WEIGHTS FROM COTTAM 119 In other instances, the case for the commercial use of lead weights is strong. At Kaupang, Norway, the introduction of lead weights in the second quarter of the ninth century (Site Phase II) corresponds with the appearance of hack-silver at the site, suggesting their role within a bullion or metal-weight economy (Pedersen 2008, 162). The lead weights and silver were spatially related, with both groups clustered in an area in which metal casting was not thought to have taken place. Significantly, the lead weights at Kaupang pre-date the appearance of the so-called ‘regulated’ copperalloy weights, suggesting that, at least in the early phases of the bullion economy, the lead weights had a primary role in weighing silver (ibid.). At Woodstown, Ireland, the weight of the thirty-one pieces of hack-silver are said to have ‘targeted on the same unit’ as the lead weights (22 g or 23 g), suggesting an association between the two artefact groups (Wallace 2013, 308). Silver was not the only commodity that might be weighed using lead weights. Accurate weight standards would have been required for measuring other trade goods, such as iron, copper-alloy, furs, textiles, and foodstuffs such as butter or grain. Indeed, as bulk goods, these products would have typically been measured out in heavier loads than transactions involving silver, and thus might be deemed suitable for use with lead weights, which could be rather heavy (weighing over 25 g or even 50 g, for instance). Of course, the weighing of silver and other commodities could also take place in other, non-commercial contexts. Such goods may have been weighed in connection to the payment of fines, taxes, or tribute, for instance, or, in the case of silver, to the division of spoil among military troops: all circumstances in which the existence of weight standards would have been desirable. Returning to Cottam B, it is worth noting that there is little evidence for on-site metalworking.5 Conversely, the inhabitants of the site were actively involved in regional trade. There is an absence of late ninth- and tenth-century coins, reflecting a broader regional decline in local coinage circulation following the Viking settlements in the 870s, but pottery from the site reflects regional trading contacts, particularly with York, north Lincolnshire and the Midlands (Blackburn 1993; Richards 1999, 97). Close trade links with York are also suggested by the find of a pewter disc brooch, similar to examples from Copperate, as well as by the presence of imported Norwegian schist hones, which were probably obtained via the town (Richards 1999, 64–5, Haldenby 1992, 32 and fig. 4.9). A commercial context for the Cottam weights therefore seems likely, although their use in other forms of transaction, such as tribute, cannot be ruled out. What can be said about the nature of the goods being weighed? Were the inhabitants of Cottam weighing precious metal for use in exchange, as a substitute for coinage? Such a scenario has been proposed at Flixborough, where excavations recovered an (undated) silver ingot, in addition to lead weights (Wastling 2009, 422). Bullion transactions, in which silver was valued by weight and purity, regardless of its form, were common in the Scandinavian homelands. They are also attested in rural Yorkshire, as demonstrated by numerous examples of single finds of hack-silver, ingots and ingot fragments, Arabic dirhams, and so-called ‘regulated’ weights (see for instance, via the Portable Antiquities Scheme website, PAS ‘Find-ID’ SWYOR-E16C55; 5 Metalworking has, however, been documented at the earlier, Anglian, settlement. Richards 1999, 91 120 DAVE HALDENBY and JANE KERSHAW figure 7 A fragmentary dirham from Cottam. FAKL-284426; YORYM-29D955; NCL-7D6F54; YORYM-30B2B5 and LVPL-16F352). Admittedly, there are few silver finds from Cottam, but the site has yielded a silver ingot of irregular form as well as a small fragment of an Arabic silver dirham (Fig. 7). The fragment, weighing just 0.17 g, was identified by Gert Rispling (The Royal Coin Cabinet, Stockholm) as a Samanid issue, minted in Tashkent, Uzbekistan, in 928/9.6 Dirhams were imported into Scandinavia and the Baltic in huge numbers and provided a crucial resource for the Scandinavian silver economy. Smaller numbers also reached England, most likely in Scandinavian hands (Naismith 2005). This find is thus indicative of contact with traders plugged into Viking trade networks. However, the coin is a single, stray find, and the means by which it reached Cottam are unclear: it may have been a casual loss from on-site trading activity, but it is equally possible that it was lost by a visitor, or simply retained as an exotic keepsake. The irregular silver ingot is likewise difficult to associate with bullion exchange, as its form is culturally undiagnostic and ingots could also be used in metalworking. In this context, it is worth noting that the weight assemblage from Cottam includes predominantly 6 Many thanks to Gert Rispling for this identification. VIKING-AGE LEAD WEIGHTS FROM COTTAM 121 heavy lead weights, which may have been inappropriate for the weighing of silver (Fig. 3). Weights of this size and weight were probably best suited for weighing staple products or bulk goods, of the type described above. The precise nature of the goods being divided by weight therefore remains elusive: what is clear is that that division took place using a weight system which would have been familiar to people of Scandinavian cultural background or to those in regular contact with Scandinavian traders. We may speculate that the inhabitants of Cottam were trading with merchants from York, but it is perhaps just as likely that their trading partners came from nearby rural settlements. Whatever the case, the weights suggest the availability and use of a Scandinavian weight unit in the rural Danelaw in the late ninth and early tenth century. Conclusions The discovery at Cottam B of a group of fifteen well-preserved lead weights represents an important new addition to the corpus of Viking-Age lead weights, which casts fresh light on contemporary lead weight forms, function and, in particular, weight standards. This paper brings this material fully into the public domain for the first time. By integrating the Cottam material with comparanda from across England, Ireland and Scandinavia, we hope to have demonstrated that the weights belong to a Scandinavian lead weight tradition, and were most likely scale weights, intended for use with hand-held balances. There has been considerable debate about the existence of weight standards in Late Saxon and Viking-Age Age England. 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Studies in Honour of James Graham-Campbell, Leiden, 301–16. Willemsen, A. 2009. Dorestad. Een wereldstad in de middeleeuwen, Zutphen. Notes on contributors David Haldenby has surveyed several Saxon sites in Yorkshire. He has published widely on Anglo-Saxon metalwork from Cottam, in particular generating new typologies for Anglo-Saxon strap-ends and collared pins. His analysis of metalwork from Cottam A and Cowlam will be published shortly. Jane Kershaw is a British Academy Post-Doctoral Research Fellow at University College London. She received her BA, MSt and PhD from Oxford University. Her research is broadly focused on the archaeology of Viking-Age Britain and Scandinavia, with specific interests in contemporary metalwork. Correspondence to: Jane Kershaw: Institute of Archaeology, University College London, 31–34 Gordon, Square, London WCIH 0PY, UK. Email: j.kershaw@ucl.ac.uk