A Masterly Hand / Scientia Artis 9

165 Pascale Fraiture 8 164 Twenty-four sequences – almost half – have fewer than seventy tree rings; of these, thirteen have fewer than fifty rings. This greatly reduces the chance of obtaining a reliable result. According to stylistic criteria, this group of sculptures is more or less con- sistent in terms of period and region; therefore the dendrochronological series from the different sculptures could be compared with each other. These comparisons made it possible to identify wood that came from the same tree (see below). They also showed good synchronisations between series from sculptures made from different trees, but likely originating from the same region. Dendrochronological averages including the ring sequences from different trees could therefore be constructed, which has two important advantages: – The trees are not all of the same age; therefore the number of rings varies. By assembling series of rings of variable lengths, the resulting average chronology is thus longer than its components and so easier to date. – By assembling ring series from different trees, the influence of the indi- vidual characteristics of each tree’s growth is reduced, while the common influence of the different oaks is emphasised, the latter being inevitably climatic. Therefore, as dendrochronology is based on the climatic signal recorded in the tree rings, averages of ring series from different trees are dendrochronologically stronger than single ser ies. 10 For the Elsloo project, the success of the results is to a great extent due to the large number of sculptures that could be analysed. Description of the Wood Used for the Elsloo Sculptures All the sculptures analysed are made of oak, Quercus robur ( pedunculate) or petreae ( sessile) (fig. 8.1). 11 Th is systematic choice of oak may be surprising, for other species are softer and thus easier to carve. But oak was considered to be of superior quality, and it had been the most commonly used wood for works of art since the Carolingian period in north-western Eur ope, 12 pa rticularly in the Southern Netherla nds. 13 Although all made of oak, several categories and qualities of wood can be distinguished. The growth rate is a primary criterion: the faster the growth ( the wider the rings), the denser and the harder the wood, making it more dif- ficult to be carved. Yet several sculptures were made of such wood, especially small statues (most of the apostles of Neeroeteren, figs. 8.4a-b), but some larger figures as well (St Agnes in Siersdorf, fig. 8.3; St Reineldis of Saintes in Neeroeteren). Knots also make carving more difficult, but these are very common (St Lucy and St Agnes from Siersdorf, figs. 8.1 and 8.3). Thus it appears that the sculptor(s) did not select the most easily worked material. On the contrary, observation of these sculptures tends to show that the selection of the wood was made on a different basis: the trunk was chosen whose shape and dimensions were most suited to the planned sculpture. This is very well illustrated by the St Anne with the Virgin and Child in Sint-Truiden, which has been carved from a bifurcating section of trunk (fig. 8.6). Other examples are Judas Thaddeus (?) in the Museum Catharijneconvent of Utrecht, whose attribute has been carved from a knot (fig. 8.7), and the St Christopher of Fig. 8.5 Dendro-data acquisition a Recording of the ring series by macro photography on the underside of St Quirinus of Malmedy, Gerdingen, Church of Our Lady b Millimetric scale placed on the underside of the Gerdingen St Quirinus to calibrate macro photographs c Example of a macro photograph of the ring series with millimetric scale d Measuring the ring series on the computer screen using specific software 8.5 a 8.5 b 8.5 c 8.5 d