4 COMPOSITIONAL EVIDENCE

The Detroit portrait is painted on a larger panel than the Uffizi portrait, though both are poplar. Preliminary investigation suggests that neither have been trimmed. The Detroit panel is 6.5 cm higher and 4.0 cm wider. The vertical joins in the panel fall awkwardly, each running through one of Eleonora's arms. In the Uffizi portrait, the center panel appears to be wider, with the vertical joins in the background to either side of her figure. The larger panel in the Detroit portrait has resulted in an extension of the image on the right and left sides and at the bottom of the composition.

Preliminary measurements of the figures in each portrait demonstrate a close correspondence in dimension. The measurements of the Uffizi portrait were taken through the glazing; therefore a certain percentage of error is presumed. However, overall there was a close correspondence between the sizes of the faces and torsos of Eleonora and Don Giovanni in the two portraits. Most of the measurements were identical or within one centimeter of each other. For example, the distance between the top of Eleonora's head and the bottom of her proper left cuff is 47.3 cm in each portrait.

The measurements support the use of a cartoon to produce the Detroit portrait, though no underdrawing was found with infrared reflectography, perhaps because of the extensive use of carbon black in the dress. An exact-size cartoon of the sitters was most likely made by the workshop, perhaps from the Uffizi portrait. The copyists did not bother to trim the panel to exact size, which would seem to have been an easier proposition than expanding the image. This decision implies a certain confidence in the copying process, which would more likely be found when a replica was being produced by the original artist's workshop. In fact, Bronzino's use of a cartoon to execute an expanded copy of a portrait of Cosimo de'Medici has been proposed elsewhere (Simon 1983).