Charcoal layer

About This Material

A layer of charcoal was one of the first signs, after the flagstones and the oak platforms, that the shaft Daniel McGinnis and his companions found in 1795 had been dug and deliberately refilled. The Onslow Company, which reopened the pit in 1804, reported layers of charcoal, putty and coconut fiber at specific levels as it dug toward ninety feet. Jotham McCully, manager of the later Truro Company, wrote in 1862 that the Onslow men found "some charcoal and some putty" among the marks they met every ten feet. James McNutt, who worked on the island in 1863, placed the tier of charcoal at forty feet, with smooth beach stones at fifty, coconut rind and grass at sixty and putty at seventy. Other accounts put the charcoal at about thirty feet. The discrepancies are typical of the early record, which was written down some sixty years after the events it describes. None of the charcoal from the 1804 excavation is known to have been kept.

Charcoal had several uses aboard ship and ashore: purifying drinking water, making gunpowder, and serving as a smokeless fuel. Graham Harris and Les MacPhie, the geotechnical engineers who wrote Oak Island and its Lost Treasure, offer a functional explanation for its presence in the shaft. The greatest obstacle for anyone working deep underground is fresh air. In the seventeenth century miners began ventilating shafts and tunnels with a furnace: a fire at the base of a chimney draws stale air up and out, pulling fresh air down behind it. The method came from the coal mines around Liège and was first described in English by Sir Robert Moray in a lecture to the Royal Society of London in July 1665. Military engineers used the same technique when digging mines under fortifications in siege warfare. Because a flue needs to be at least thirty feet long to draw well, Harris and MacPhie suggest the charcoal marks a ventilation furnace installed about thirty feet down inside the shaft, which would also have kept most of the chimney out of sight. Since Agricola's De Re Metallica of 1556 does not mention furnace ventilation, they take the charcoal as a sign that at least part of the workings was dug after the Liège practice became known, that is, after 1665.

A separate charcoal sample, recovered by Dan Blankenship in 1970 and radiocarbon dated to about 90 BC, has its own entry in this catalogue. It has not been tied to the charcoal layer reported in the Money Pit in 1804.