Page 49 - Loss of the VOC Retourschip Batavia, Western Australia, 1629

THE COMPOSITE GUNS
The two composite guns. No. 7 BA T 3642. raised by
the Western Australian Museum in 1973. and gun No. 22 BA T 3641. recovered in 1963. are of particular interest. The guns seem to be identical and are remarkable in
their external appearance. being 2.284 m long with a bore of0.147m.andasinglereinforce.Whatmakestheseguns unusual. is the fact that they appeared. at first. to be made of rolled copper sheet. with the breech. chase-girdle. and muzzlemadeofcoppermouldings.Thetrunnionsarealso copper and were attached to the chase-girdle. Three astragals on the chase-girdle and single astragals on the brcech and muzzle. make up the simple mouldings. The Avac monogram is inscribed on the first reinforce. to- gether with the figures 1715A (its weight in Amsterdam pounds) on the base-ring of BA T 3642 and 1830A on BAT 3641. Two bronze. pommel-shaped objects were found on the wreck site near these guns. These were clearly part of the cascabel. the iron attachments having corroded away. causing them to drop off. The cascabel has a touch-hole. which explained its absence on the vent- field.
BA T 3642 had a hole torn in the copper sheeting. revealing lead sheeting underneath and, beneath this. iron bands. The iron bands appeared to be spaced with lead washers and more lead sheeting could be seen underneath. As it was far from clear exactly how the gun was con- structed. an investigation of this was made.
Initially. a radioactive cobalt source was used to produce radiographs of the gun. These showed the struc- ture to be exceedingly complex and difficult to interpret. It was finally decided to section the gun as the most effective means of discovering how the piece was con- structed and of determining the extent of the corrosion under the copper sheeting and. thus. the conservation requirements. The other option would have been to dis- mantle the gun by removing the copper sheeting. and working through the gun. layer by layer. butit was thought this might cause irreparable damage. The sectioning approach seemed more flexible. for one could study the section and then display it or replace i~ with a repair to the gun. Accordingly. a wedge-shaped slice. including the damagedsectionofthechase.wascutout.IttoOk80hours with an·angle-grinder to cut through and remove the wedge. The sections were then ground smooth and pol- ished (Fig. 28).
Examinationofthewallsofthecutsectionshowedthe eXlIemely unusual construction quite clearly. Beneath the copper outer skin were a series of 30 iron bands Or hoops shrunk onto a series of flat staves. The gun is, in fact, a wrought iron gun enclosed in a copper case with the spaces filled-in by pouring molten solder. The gun was chambered; the chamber being about 400 mm long with a complex construction. Corrosion had occurred in the chamber. so that its exact structure was not clearly de- fined. The cascabel was originally attached to an iron
screw. it seems likely that this could be screwed outofthe gun by inserting a bar into the hole in the cascabel. The cascabel was cast onto the iron screw. and a hole drilled down the centre to form the touch-hole channel. A vertical hole ran from the touch-hole pan on the top ofthecascabel to this horizontal hole. A small screw thread at the very
end of the cascabel allowed the end to be sealed off.
By chance. the cutting revealed that what appeared to be an iron tube was. in fact. split. Comparison with the x- ray photographs indicated that this was part of a series of six iron bars or staves. forming a tube. Closer examination ofthe mouldingaroundthetrunnions.showedthatthefour circles On the x-ray corresponded to four copper patches. eachcoveringahole.Thesewererepeatedonbothsidesof the moulding and may represent some method ofpinning. A chemical analysis of the non-ferrous metal showed thatcoppersheetingwas98.85%Cu.Theleadwas.infact. solder. with 69.8% Pb and 28.0% Sn. The cascabel was a
bronze 71.9% Cu, 24.3% Pb. 3.05% Sn.
It seems. therefore. that the gun was constructed in the
following manner. A copper sheet forming the bore was set onto a mandrel. Onto this were mounted six flat. iron staves, held in place with the wrought-iron bands or hoops which were probably heat-shrunk in place. The chamber was fitted into the end of the piece. and the staves ham- mered over to lock it into place. Iron pins were mounted around the trunnions. and the trunnions fitted on in an (at present) unknown way. The outer copper sheathing was moulded around the gun. using the pins to locate and centre the ironwork. Presumably. the whole was covered in clay. up-ended (breech up) and heated. The molten solder was then poured into the top until the interior was ruled up. The cascabel-disk was then soldered into place, and the clay and mandrel removed.
These guns have a calibre capable of firing 24 pont balls, (if, indeed, they ever frred solid shot). This is an enormous calibre for the weight of the piece (1715 Amsterdam pont).
Van Darn (1701) records that on the 22 August 1630, the vac specified two mignons as part of the armament of a retourschip (Staple, 1927:507). so it is possible that these two composite guns were mignons. They do not, however, correspond to the specification for mignons given by 17th-century writers on artillery. In particular, Norton (1628) describes a mignon weighing 1200 Ibs, with a bore of 3.25 (83 mm) inches and frring a 3.75 Ib (1.70 kg) shot. SllIple (1927). suggests that the mignons mentioned by van Dam are the smallest type of ships' cannon. The composite guns from theBatavia have a bore equal to the four large bronze guns from the site although they are almost half the weight.
Since the composite guns had a chamber, they may p o s s i b l y h a v e b e e n a t y p e o f perior . T h e perior (perrier o r pierrier) was originally a breech-loader. firing stone shot; later. they became muzzle-loaders and eventually they fired iron shot. In the later periods. they seem to be characterized by the chamber at the breech. which was re- quired to increase the stIeng,l! of the gun since it was
usually lightly-metalled. Norton. one of the few 17th- century English writers to describe perior in this period. states: 'most foreign Cannon Periorsarechambered, being eyther taper or belbored in their chambers'. Since the chambers of the Batavia guns were tapered it is possible that they wereperiors firing murthering (Norton) sho~ no stone shot having been found on the wreck site. This would also explain their light weight in comparison with ordnance ofa similarcalibre. Norton (1628) sllltes that' for
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