Knappers' rot. Silicosis in East Anglian flint-knappers.

ALONG THE line of the prehistoric trackway Icknield Way, a ridge of chalk, five miles wide, extends through west Norfolk to north-west Suffolk.' Beneath it lies-a seam of floorstone flint that Neolithic men exploited when they dug a series of large and elaborate mines to extract the flint at a site in south-west Norfolk now known as Grime's Graves. Over the succeeding four thousand years when this same flint lay near the surface it no doubt continued to be used for flint implements and later for building houses, churches, and for other purposes. Then at the end of the eighteenth century a second series of mines was dug into the chalk ridge at Brandon, a Suffolk market town three miles south-west of Grime's Graves, when Brandon became the main source of supply of gunflints for the British army. In his Milroy lectures for 1915, Collis2 suggested that the Neolithic miners at Grime's Graves may have suffered from silicosis and conjectured that this might be the oldest occupational disease.3 He also reported on a study of the second period of East Anglian flint mining and showed that the exposure of the Brandon gunflintknappers to silica dust caused an excess mortality from pulmonary tuberculosis, known locally at the time as "knappers' rot".4 Collis's observations have often been