Page 27 - Loss of the VOC Retourschip Batavia, Western Australia, 1629

FigureIS. Placingasmallexplosivechargeonthecannonballconcretion.ThediverisplacingBDelectricaldetonatorinthecordtex train, which will set off the two small charges on the rubber mal
On the main site, divers who were excavating placed
their small finds in a bag. On return ID the workboat at the
endoftheday,eachbagofartefactswaskeptintac!.Since
each diver worked in one particular area (rarely more than
2 m square), it was possible to identify the location of the
artefactsonalarge-scaleplanofthesiteIDwithin0.5to1.0
m. Backatthefieldstation,attheendofthework-day,each
person sorted their finds out and indicated their location on
alarge-sealeplanofthesite.Thisplanwasgriddedintoone ationsintheverticalcomponen!.OntheBataviasite,itwas metre squares; the grid lines running north-south and east-
west and numbered systematically.
The location of a find was then recorded in the same way as a map reference, with a six-figure number. The fust three figures referred to the northing and the last three the easting. Space was provided in the registers for further infonnation, such as photograph numbers, weights, di- mensions etc. The exact location of loose fmds from the inside reef site was not recorded, since the material had traveled more than 1 km from the main site, and was distributed in a random fashion over an area lOOm long by 50 m wide. Wherever possible, identifiable objects were photographed (see photographic record) and drawn on plastic drafting mm with Indian ink at a 1:1 scale (where practicable). In as far as circumstances allowed, artefacts were studied at the field station.
or pulling on the right-angle frame. 15
This close examination of material while in the field
was found to bemostrewarding, particularly with ceramic
material,whereitwasstillpossibletoreturnIDthefmdspot theappropriatesideofthewire.Somecarewasrequiredto to search for missing pieces. ensurethatthebase-linewirewasnotdisplacedbypushing
Underwater recording
Various types of site recording were carried out from
time to time as the need arose. The original survey of the site was carried out in 1971 by a Museum expedition. However, there appeared ID be some minor discrepancies in the plan when it was compared with the site. Trilaters- t i o n w a s u s e d ID p l o t t h e p o s i t i o n o f m a j o r a r t e f a c t s d u r i n g the ftrSt survey, but because of the undulating nature of the site, it is likely that these discrepancies are due to vari-
difficult to make accurate measurements with tapes be- cause of the strong surge. This technique was abandoned because of these problems. Instead, a simpler and cruder system was adopted to obtain areasonablyaccurate survey in a short period of time.This system consisted of a taut wire base-line run out over the long axis of the site from position 000108 to 460108. A sliding right-angle frame was constructed to run through the base-line. Objects were co-ordinated by sighting along the arm o f the frame atright angles to the wire. By adjusting the position of the frame on the wire, it was possible to get an exact sighting on an object, so that the object lay in line with the right-angle arm of the frame. Thus, by measuring the distance along the wire and the distance from the wire along the right-angle arm to the object, it was possible to detennine its position. Noattemptwasmadetocorrectfortheheightoftheobject, relative to the base-line wire. Objects on either side of the base-linecouldberecordedbysimplyrotatingtheframeto