Over the past thirty years our understanding of the Roman glass vessel industry has been transformed, but there is still much we do not know about it. It is now appreciated that the debris from glass-blowing with its very characteristic moiles (the glass from the end of the blowing iron) is not uncommon in the Western Empire. Generally, however, it has not often been found usefully associated with the structures from which it was derived. The two books under review illustrate our problems.

The first provides very full details of the glass-melting emplacements found in the lower town of Kaiseraugst (outside modern Basle) during excavations in 1974 and 1978. The second is not in the same league as the Augst book, being a small popular guide designed to tell a lay public about the glass-working evidence of Roman London with special emphasis on the finds from 35 Basinghall Street recovered in 2005. There over 70 kg of glass debris with some furnace material included all the debris from every stage of glass-blowing from the raw chunks of glass to the failed wasters. The excavations did not produce any evidence of in-situ furnaces. Common to both books are pictures by Mark Taylor and David Hill, producing replicas and showing the techniques (see http://www.romanglassmakers.co.uk/).

At Kaiseraugst parts of two buildings on the angles of a crossroads retained a variety of furnace structures. The one excavated in 1974 had a single circular furnace, while the other site had a total of eight circular furnaces and six rectangular ones. Three of the latter were clearly tank furnaces for melting glass, while the temperatures reached within the circular ones would have enabled them to melt the contents of the glass-melting pots of which a minimum of 51 were recovered. The other three rectangular furnaces reached lower temperatures and it is suggested that these were annealing ovens to allow the finished products to cool down in a controlled manner so that they did not shatter. A stratified sequence showed that one of the tank furnaces which had had two phases of use was replaced by two superimposed annealing ovens. In two cases circular furnaces were superimposed on each other, and in all, five phases of activity are suggested during the second century and running into the third. There can be no doubt that a considerable amount of glass was melted here, but what was it used for?

Other than the glass attached to the walls of the tank furnaces, and on the insides of the glass-melting pots, the amount of waste glass appears to be quite small. Only six fragments of moiles were found (112) and they are the definitive evidence for glass-blowing. As the London book reminds us (55) every blown glass vessel produced would have been associated with a moile. The Kaiseraugust total can be compared with the 1,500 complete moiles with a further 6,000 fragments from Basinghall Street (39). Indeed Fischer himself compares the total to the 5,000 moiles found at Avenches. Even a relatively small group of blowing waste such as the one kilogram found at Wroxeter had well over 200 fragments from moiles (J. Price and S. Worrell, in P. Ellis and R. White, Wroxeter Archaeology: Excavation and Research on the Defences and in the Town, 1968–1992 (= Shropshire Archaeological and Historical Transactions 78) (2006), 138 nos 49–55, col. pls 2–4, 6–7). It would have been helpful if the weights of the different categories of glass waste at Kaiseraugst had been given, so that the proportion of moiles could have been judged. As the evidence stands, though some glass-blowing was being carried out, it scarcely accounts for the volume of glass that must have been melted there over the years.

Window and bottle fragments are present but not in any great quantities and probably as cullet (broken glass destined to be recycled). In the case of the window glass this is confirmed by the fragments of mortar they retain from their previous use (Abb. 128). A similar phenomenon can be seen at London (37). Window glass and chunks of prismatic bottles were a useful form of cullet as the pieces were quite thick and provided more glass than the equivalent area of other vessel forms. The author explores the possibility that one product would have been the very common square bottles which were in use during the period the establishment was active; but they too are blown and their production would have created moiles. Unless this workshop was kept very clean during its life and the majority of the waste glass removed when it went out of use, the scarcity of moiles would argue against large quantities of blown vessels being produced there.

To a certain extent the evidence seems similar to that from York published in this journal a decade ago where glass was being made from raw ingredients (H.E.M. Cool, C.M. Jackson and J. Monaghan, ‘Glassmaking and the Sixth Legion at York’, Britannia 30 (1999), 147–61). There it was suggested that the glass-melting pots might have been used in the manufacture of cast window panes. At Kaiseraugst there is no evidence for manufacture from raw materials, and the production of window glass is considered but rejected.

So the Kaiseraugst establishment, despite being one of the best sets of structural remains for the working of glass in the Western Empire, remains something of a puzzle. Andreas Fischer, though, has provided us with a splendid report that one day might help us solve it. The book is very well produced with colour used throughout. This is especially useful for the glass as clearly some unusual colours were being melted (a very dark green appearing black and a dark blue/green: Abb. 125, 127). The stratigraphy is well presented, there is a full report on the glass-melting pots and some interesting reconstructions of the furnaces. All in all a very useful book for anyone interested in high temperature industry.

The little London book, too, is beautifully illustrated, provides some useful interim information, and whets our appetite for the results of the ongoing analysis. The site developers who sponsored it are to be thanked.