The mass was cemented together by a combination of fine, black mud and lime kiln waste. The black mud was formed from night soil waste and was very tenacious. It ranged in consistency from very soft and clayey to compact and hard, similar to Jurassic mudstone such as that you can find on Dorset beaches. Iron salts from the decomposition of ferrous objects made it extremely hard in places. The lime kiln waste was identified as such by analysis undertaken by the Scottish Lime Centre. Like the night soil, it had been dumped upon the mass of machinery etc. from above through a doorway to the alley. Much of the lime had taken a very strong set, like concrete.
The deposition sequence was as follows:
Thick layer of sawdust, wood shavings and off-cuts, 10-15 cm deep sitting directly on the dock floor. There were a few fragments of broken pottery incorporated, including most of a Delft Willow Pattern eggcup. The thickness of the layer and the incorporation of pottery waste strongly suggest it was the result of dumping through the doorway above, of waste from a workshop, rather than of works to boats (i.e. Peggy) in the dock itself.
Machinery components, metal implements, scrap timber. This would appear to be a single deposit, judging from the extremely complicated tangle. There are items from what might best be described as a workshop clear-out: miscellaneous cast iron boxes, one of which contains a flintlock, a key and other oddments; hinge plates and cast iron collars; keys; a set of weighing scales; an auger and a variety of long bars with hooks or T-pieces. The machinery components are distinct from these. They are characterised by substantial and refined castings and finely made gears. They are often composite with wooden parts. They include a number of crank pieces designed to transmit rotary motion to lateral, reciprocal movement, driven by a beveled gear and a separate drive shaft; one of these pieces incorporates a very unusual belt-drive cylinder.
|Part of an elaborate cast iron cam with wooden rods|
There is also a rather fine regulator – a long rod, pivoted in the middle, terminating in lead spheres at either end. The two large wheels, one with four spokes and the other with six, are also from this group. The strong indication is that all the machinery components come from one machine unconnected to the dock.
Night soil, as above described.
Lime waste, ditto.
Glass and pottery waste, added while the night soil and lime were soft.