Lamps of this type look like small casseroles, hence the German appellation Tiegellampen (crucible lamps). Bailey has doubts about the lighting function of these vessels and does not include them in his catalogue (Bailey BM III, p. vii). As he points it out, they do not have a nozzle or even an open wick-place like Loeschcke type XI; no traces of burning have ever been noticed on their rims. In her 1997 publication, published nine years after Bailey BM III, Goethert still accepts them as lighting devices, as Loeschcke did in his time, and as several authors have since, for instance, recently Bémont. We will include the only Getty example in this catalogue, leaving the issue open.
Did these open lamps burn tallow? Loeschcke asked the question and was inclined to answer negatively because of their presence in Pompeii, where olive oil was the usual abundant and cheap lamp fuel. Leibundgut considers that open lamps, including Tiegellampen, may have burned wax or tallow rather than oil (Leibundgut 1977, pp. 57–58). Actually, the lamps probably burned either, depending on which was the cheaper fuel in any given geographical region. Goethert favors oil (Goethert 1997, p. 148), although in Trier tallow would be the expected fuel, as it is in Avenches or Bern.
In the Trier material Goethert identifies seven different profiles of Tiegellampen: her variants a–g (Goethert 1997, p. 148, fig. 87). The wide opening on the top of the vessel, sometimes with a lip, varies in diameter. The profile of the body varies between biconical and biconvex. In Goethert’s variant g the general silhouette of the remarkably small lamp evokes a lens, hence the German appellation of Linsen-förmige Tiegellämpchen.
Tiegellampen have been found in nearly all parts of the Roman Empire. The type is well documented in central and northeastern Gaul, in Switzerland, the Rhine Valley, Aquileia, north of the Alps, in Pannonia, and in the Danubian plain in the Balkans. Isolated examples have been found in Spain, Cyprus, and the Palmyra region. Loeschcke writes, “In Pompei kommen Lämpchen des Typus XIII zahlreich vor” (Loeschcke 1919, p. 306), although the type is not mentioned by Pavolini, in Carandini et al. 1977. For references to these geographical locations, see Di Filippo Balestrazzi 1988, vol. 2.1, pp. 81–86, and vol. 2.2, pls. 13–14 (Aquileia); Larese 1983, no. 115; Hübinger 1993, p. 102, no. 187; and Bémont and Chew 2007, p. 227.
Different dates for Tiegellampen, all forms included, have been suggested: Early Flavian to second and third centuries (Loeschcke 1919); first and second century A.D. (Di Filippo Balestrazzi 1988, vol. 2.1; Bet, Gangloff, and Vertet 1987); first to third century (Leibundgut 1977); second half of first century to mid-third century A.D. (Goethert 1997); and mid-first century to beginning of third century (Bémont and Chew 2007).