Coade, Blashfield or Doulton? The in situ identification of ceramic garden statuary and ornament from three eighteenth and nineteenth century manufacturers

In the eighteenth century, the emergence of a neo-classical style in architecture created a growing demand for a range of classically-inspired products - not only for architectural decoration but also for ornamentation of the garden. Producing individual items in stone, however, was time-consuming and expensive, so cheaper clay-based alternatives were adopted, most notably from manufacturers such as Coade (1769-1830), Blashfield (1840s-1875) and Doulton (1854-1890s). The artefacts of these manufacturers are now considered of high historic value and significance and their identification is important, not only for the historical record, but also for provision of the evidence necessary to carry out informed conservation. As the sale and copy of moulds was common practice during the eighteenth and nineteenth centuries, stylistic considerations do not provide reliable identification. Through the analysis of 24 historic objects of garden statuary and ornamentation, this research evaluates the use of portable X-ray fluorescence spectroscopy (pXRF), and more specifically element profiles, in identifying, and differentiating between the products of Coade, Blashfield and Doulton. Key questions around heterogeneity and representative material analysis are addressed. Despite the inherent heterogeneity of these materials, it is shown that discrimination is nevertheless possible using pXRF, primarily due to the significant differences observed across a range of elements at both macro- and trace-level. Objects of known provenance from Coade, Blashfield and Doulton produced three distinct and statistically significant groups demonstrating that the data reflect the composition of the bulk material – rather than surface characteristics. Through identifying the main discriminators for the Coade, Blashfield and Doulton materials, a simple presumptive test is proposed that can be used in an initial evaluation of any unsigned works. Analysis of a selection of unsigned objects with a probable Coade, Blashfield or Doulton provenance was in many cases successful in confirming the documentary evidence. A few objects, however, presented anomalous element profiles. These most likely result from past conservation treatments or polychromy - the two major limitations of the technique

Risk assessment and risk management of violent reoffending among prisoners

“The final publication is available at Springer via http://dx.doi.org/10.1016/j.eswa.2015.05.025”

Composition, production and procurement of glass at San Vincenzo: an early medieval monastic complex in southern Italy

136 glasses from the ninth-century monastery of San Vincenzo and its workshops have been analysed by electron microprobe in order to situate the assemblage within the first millennium CE glass making tradition. The majority of the glass compositions can be paralleled by Roman glass from the first to third centuries, with very few samples consistent with later compositional groups. Colours for trailed decoration on vessels, for vessel bodies and for sheet glass for windows were largely produced by melting the glass tesserae from old Roman mosaics. Some weakly-coloured transparent glass was obtained by re-melting Roman window glass, while some was produced by melting and mixing of tesserae, excluding the strongly coloured cobalt blues. Our data suggest that to feed the needs of the glass workshop, the bulk of the glass was removed as tesserae and windows from a large Roman building. This is consistent with a historical account according to which the granite columns of the monastic church were spolia from a Roman temple in the region. The purported shortage of natron from Egypt does not appear to explain the dependency of San Vincenzo on old Roman glass. Rather, the absence of contemporary primary glass may reflect the downturn in long-distance trade in the later first millennium C.E., and the role of patronage in the “ritual economy” founded upon donations and gift-giving of the time

Seventh to eleventh century CE glass from Northern Italy: between continuity and innovation

Previous analytical studies show that most of Northern Italian glass has been heavily recycled and that mixing of natron and plant ash glass was occurring (Verità and Toninato 1990; Verità et al. 2002; Uboldi and Verità 2003; Andreescu-Treadgold and Henderson 2006; Silvestri and Marcante 2011). The re-use of “old Roman glass” has been interpreted as stagnation in glass trade from the primary production areas. However, the reintroduction of plant ash glass on sites such as Torcello, Nogara, and in Lombardy at the same time as it was reintroduced in the Levant, strongly indicates long-distance contacts with the Levant at least from the eighth century CE. This paper addresses the key issue of recycling by focusing on the compositional nature of glass traded and reworked in Northern Italy after the seventh century CE set in a broad Mediterranean context by analysing major, minor, and trace elements in eighty-nine glass samples (seventh to the eleventh century AD) from the glass workshop of Piazza XX Settembre, Comacchio. Five major previously proposed compositional groups of glass have been identified from Comacchio (Levantine Apollonia and Jalame types, HIMT, Foy-2, and plant ash glass). The impact of recycling and mixing practices in Comacchio glass is also discussed with the help of known recycling markers and selected ratios (major and trace elements). The mixing between Levantine, HIMT, and plant ash glass is highlighted and end-members of potential natron to natron mixing compositional groups have been identified. The compositional nature of plant ash glass from Northern Italy is discussed in light of their trace element content and production areas

Late Byzantine Mineral Soda High Alumina Glasses from Asia Minor: A New Primary Glass Production Group

The chemical characterisation of archaeological glass allows the discrimination between different glass groups and the identification of raw materials and technological traditions of their production. Several lines of evidence point towards the large-scale production of first millennium CE glass in a limited number of glass making factories from a mixture of Egyptian mineral soda and a locally available silica source. Fundamental changes in the manufacturing processes occurred from the eight/ninth century CE onwards, when Egyptian mineral soda was gradually replaced by soda-rich plant ash in Egypt as well as the Islamic Middle East. In order to elucidate the supply and consumption of glass during this transitional period, 31 glass samples from the assemblage found at Pergamon (Turkey) that date to the fourth to fourteenth centuries CE were analysed by electron microprobe analysis (EPMA) and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The statistical evaluation of the data revealed that the Byzantine glasses from Pergamon represent at least three different glass production technologies, one of which had not previously been recognised in the glass making traditions of the Mediterranean. While the chemical characteristics of the late antique and early medieval fragments confirm the current model of glass production and distribution at the time, the elemental make-up of the majority of the eighth- to fourteenth-century glasses from Pergamon indicate the existence of a late Byzantine glass type that is characterised by high alumina levels. Judging from the trace element patterns and elevated boron and lithium concentrations, these glasses were produced with a mineral soda different to the Egyptian natron from the Wadi Natrun, suggesting a possible regional Byzantine primary glass production in Asia Minor

Bifurcation analysis of two coupled Jansen-Rit neural mass models

We investigate how changes in network structure can lead to pathological oscillations similar to those observed in epileptic brain. Specifically, we conduct a bifurcation analysis of a network of two Jansen-Rit neural mass models, representing two cortical regions, to investigate different aspects of its behavior with respect to changes in the input and interconnection gains. The bifurcation diagrams, along with simulated EEG time series, exhibit diverse behaviors when varying the input, coupling strength, and network structure. We show that this simple network of neural mass models can generate various oscillatory activities, including delta wave activity, which has not been previously reported through analysis of a single Jansen-Rit neural mass model. Our analysis shows that spike-wave discharges can occur in a cortical region as a result of input changes in the other region, which may have important implications for epilepsy treatment. The bifurcation analysis is related to clinical data in two case studies

Technology and provenance study of Levantine plant ash glass using Sr-Nd isotope analysis

Book description: The products of Byzantine glass-making workshops are found throughout the whole of the Mediterranean area and were also distributed into regions far beyond the borders of the Empire. Research into glass production and distribution in Byzantium has made enormous progress, especially in the last years. Thanks to state of the art scientific methods and a number of recent discoveries, it is not only possible today to identify centres of raw glass production, but also to trace additional trade routes to secondary workshops. Furthermore, the results of this research have revealed details of the formulas used in glass production, the source of the raw products and the technologies employed. The current state of this research was the subject of discussion at an international workshop hosted in January 2008 by the "Byzantine Archaeology Mainz". Contributions to this conference dealt with a geographical area between North Afrcia, the Balkans, Asia Minor and the Near East. The focal point of the workshop was formed on the one hand by results of scientific analyses of glass and on the other hand by studies of regionally-specific expressions of Byzantine forms of glass. Thus research into Byzantine glass manufacture has once again produced highly interesting findings and permitted an insight into the diverse possibilities of modern analytical methods