In 1844, Sir David Brewster (1781-1868, inventor of the kaleidoscope in 1816) reported to the British Association for the Advancement of Science that a nail had been discovered firmly embedded in a block of sandstone from the Mylnefield Quarry, near Kingoodie (Perth & Kinross, Scotland). The sandstone block was stated to have been 229 mm (3 inches) thick and was discovered when the rock was being dressed, at which point it was projecting about 13 mm (½ inch) into the ‘till’ (boulder clay) and very rusty. The rest of the nail was found to lie against the surface of the stone to within 25 mm (1 inch) of the head, which was the only part actually embedded in the stone.

Another apparently well documented story. But it is clear that all is not well: far from being embedded in the sandstone, the nail was basically lying against its exposed surface beneath the overlying boulder clay. If 25 mm were actually embedded in the stone, we do not know what proportion of the nail this represents: a quarter? an eighth? And what did Brewster mean by ‘firmly embedded’?

There do not seem to be any further accounts of this object and I have not been able to find any photographs of it: its status is unresolved, but it falls into a well documented pattern of early to mid nineteenth-century reports of scientific curiosities. Such reports tail off into the later part of the century and – creationist tracts apart – disappear early in the twentieth. This is not because of a conspiracy of scientists to hide truths that undermine their shaky edifice of weak hypotheses but because such ‘puzzles’ no longer seem so puzzling.