The Brass Nails of the Akko Tower Wreck (Israel): Archaeometallurgical Analyses

Metallogr. Microstruct. Anal. (2015) 4:188–206 DOI 10.1007/s13632-015-0203-7 TECHNICAL ARTICLE The Brass Nails of the Akko Tower Wreck (Israel): Archaeometallurgical Analyses M. Cohen1 • D. Ashkenazi2 • Y. Kahanov1 • A. Stern3 • S. Klein4 • D. Cvikel1 Received: 1 January 2015 / Revised: 24 March 2015 / Accepted: 1 April 2015 / Published online: 24 April 2015  Springer Science+Business Media New York and ASM International 2015 Abstract The shipwreck designated as the Akko Tower Wreck was discovered inside Akko harbor, Israel, in 1966. It was surveyed in 1975 and 1981, and excavated in 2012–2013. Hull planks were connected to the frames by brass nails, some of which were in situ, emerging vertically from the planking, where frames had disappeared, and others were detached. The 105 nails that were retrieved were tentatively divided into two groups (A and B) according to their general shape and size. Nails sampled from each group were characterized by non-destructive and destructive metallurgical methods, including XRF, light microscopy, SEM– EDS, microindentation hardness measurements, and lead isotope analysis, in order to reveal their composition and microstructure, as well as to determine their manufacturing process and date the origin of the raw material. All nails were manufactured by casting and made of binary copper-zinc alloy: Type A with 35–36 wt% zinc, and Type B with 33– 34 wt% zinc (XRF results). These compositions confirmed the preliminary typing of the nails. Their microstructure indicates that they were manufactured differently: Type A nails have Widmanstätten thin lamellae plates, and Type B nails have a-brass grains containing a dendritic & D. Ashkenazi 1 Leon Recanati Institute for Maritime Studies, University of Haifa, 3498838 Haifa, Israel 2 School of Mechanical Engineering, Tel Aviv University, 6997801 Ramat Aviv, Israel 3 Department of Materials Engineering, Ben-Gurion University of the Negev, 8410501 Beer Sheva, Israel 4 Institut für Geowissenschaften, J. W. Goethe Universität, Altenhöferallee 1, 60438 Frankfurt, Germany 123 microstructure. Based on their zinc and lead concentrations it is suggested that the nails were manufactured in the first half of the nineteenth century. The lead isotope analyses of the nails suggest that the raw material most probably originated in Great Britain. Hence, it is suggested that the Akko Tower Wreck is the remains of a European merchantman which sank in Akko harbor about the middle of the nineteenth century. Keywords Akko Tower Wreck
Brass nails
Casting
Lead isotope
Microstructure
Metallography Introduction The Historical Setting The historic walled port city of Akko (Acre, St. Jean d’Acre, Akka) lies at the northern extremity of Haifa Bay, in the north of Israel (Fig. 1). It has a continuous settlement history from the Early Bronze Age to the modern era, serving as an important port [1–3]. The town and harbor were conquered by the Ottomans in 1516 [3]. The restoration and fortification of the town was begun by Daher al-Umar in the mid-eighteenth century [3, 4, p. 133]. In the second half of the eighteenth century, Akko became the de facto capital of the Holy Land, as well as its principal trading port [4, p. 134]. In August 1775 Ahmed Jezzar Pasha captured Akko, and made it the center of his authority. By the late 1780s Jezzar Pasha had a small fleet of seven warships, some of which were merchantmen which he armed with cannon salvaged from shipwrecks [4, pp. 290–291]. In 1799, British control of the sea and the harbor of Akko with its fortifications and defenders prevented Metallogr. Microstruct. Anal. (2015) 4:188–206 189 Fig. 1 Location of Akko and the Akko Tower Wreck (Drawing: N. Yoselevich and J. Asuli) Napoleon Bonaparte from taking the town and stopped his advance northwards [5, p. 28, 6, pp. 372–373, 7]. Muhammad Ali’s Egyptian flotilla bombarded Akko heavily in December 1831. The defenders of Akko withstood the attack from the sea, and the Egyptian ships were severely damaged. After a 6-month siege, on 27 May 1832, the Egyptians took the town by land. The period of Egyptian rule over Akko lasted until 3 November 1840, when a British–Austrian–Ottoman fleet bombarded the town. During this attack, the main powder magazine of Akko exploded, causing enormous damage to the town, which was taken the following day [5, pp. 39–48, 6, pp. 561–564, 8]. Although the town was heavily damaged and her fortifications destroyed, ships continued to call at the harbor, which was also a starting point for research expeditions to the Holy Land. For example, in August 1847, T. H. Molyneux launched an expedition from the 26-gun frigate HMS Spartan, to the Dead Sea from Akko [9]. In March–April 1848, the USS Supply anchored near Akko, from where W. F. Lynch started his expedition to the Jordan and the Dead Sea [10, 11]. In 1860, A. L. Mansell, 123 190 Metallogr. Microstruct. Anal. (2015) 4:188–206 with HMS Firefly, surveyed the bay of Akko and the town [12]. These land and naval campaigns were a result of Akko being considered the key to the Holy Land and Syria, and its conquest marked the change of control over the whole country. At the same time, Akko harbor served for commercial purposes and for survey expeditions. Consequently, ships of various types, and from various fleets— European, American, and eastern Mediterranean, used Akko harbor. The Akko Tower Wreck is probably the remains of one of these ships. The Akko Tower Wreck The shipwreck designated as the Akko Tower Wreck lies at the entrance to Akko harbor, 35 m north of the Tower of Flies, after which it was named (Fig. 1). It was discovered in 1966, and surveyed twice, in 1975 and 1981 [13, 14]. The researchers who surveyed the shipwreck came to two different conclusions regarding the original ship: (1) it was a 45-m-long warship, which was scuttled by the British during the French siege of Akko in 1799 [13, 14]; and (2) it was a 25-m-long European merchantman from the nineteenth century [15]. Following the discrepancies in their conclusions, and the scholars’ wish that the Akko Tower Wreck be further studied, it was excavated in 2012–2013 by the Leon Recanati Institute for Maritime Studies of the University of Haifa. The Akko Tower Wreck was found in 4.4 m of water. The shipwreck remains, lying north-east to south-west, were 17.8 m between its extremities, and maximum 6.4 m wide. Among the hull remains were sections of the keel, rising wood, keelson, hull planks, framing timbers, ceiling planks, and limber boards. Hull components were made of pine (Pinus) and oak (Quercus) species. The Brass Nails During the underwater excavations, a total of 105 brass nails were retrieved from the wreck-site. The majority of nails (81%) were found detached, scattered inside the shipwreck and nearby, probably as a result of the wrecking or degradation of the wood over the years, while some (19%) were removed from the wooden components (Fig. 2) (...truncated)