So far we have dealt only with errors resulting from imperfect information or too hastily drawn inferences. But there are cases in which, as we have said, an uneducated man has succeeded in deceiving a geologist in his own special line of study. The well-known jaw of Moulin Quignon is a case in point. Every one has heard of M. Boucher de Perthes' careful exploration of the gravels of the Somme Valley, which resulted in the discovery of thousands of flint implements, the handiwork of primitive man in Western Europe. But up to 1863 M. Boucher de Perthes had found no human remains in the gravel, though it had been predicted that such would be found; and he was naturally anxious to make the discovery. He had offered a reward for this purpose to the workmen of the different gravel-pits in the valley. Several attempts had been made to deceive him with false discoveries, but in every case his special knowledge had saved him from falling into a trap. At length he and many others with him were completely deceived by the cunning of a workman. In 1863 a quarryman at Moulin Quignon, near Abbeville, came to M. Boucher de Perthes with the news that he had laid bare a human bone in the gravel. He had left it undisturbed, in order that the professor might himself examine it _in situ_, and explore the surrounding deposit for further remains. M. de Perthes and some of his friends went to the spot. Half imbedded in the gravel--a bed of pebbles stained a dull red by the presence of iron in the deposit--they found a human jawbone with several teeth still in position, the whole stained like the surrounding gravel. Close by was a flint hatchet.
As soon as the news of the discovery reached England, a number of English men of science visited Abbeville. To the doubts which they expressed as to the genuineness of the discovery, M. de Perthes replied that he had himself removed the jawbone from the undisturbed bed of gravel, and that the workmen who had uncovered it were men of irreproachable character. Two conferences of French and English geologists were held, one at Paris, the other at Abbeville; the bone and teeth were carefully examined; and though many were not fully satisfied, the general impression was that the discovery was a genuine one. M. de Quatrefages expressed his opinion that it might be regarded as 'the first human fossil ever discovered except in a cave.' But among the English geologists there were some who were not so easily convinced. One of the teeth was brought to London and subjected to microscopical examination; and it was shewn that there were no signs of mineral infiltration into its structure. The tooth was like one from a recent grave. The jawbone when sawn across at Paris had emitted the odour of fresh bone. It was pointed out that the edges of the flints found with it were quite sharp and fresh; there were no signs of rounding or rolling in an ancient river. The workmen were watched. It was discovered that they occasionally found means to introduce flint implements of modern manufacture into the gravel. It was observed too that the reddish deposit on the bone could easily be imparted to the surface of bones and flints by artificial means. Suspicion was thus aroused in many quarters, when Mr Busk opened a Celtic grave not far from Moulin Quignon, and there found the skeleton of a Gaulic warrior _minus the lower jawbone_. The famous jaw of Moulin Quignon was all that was needed to make the skeleton a perfect one. For most men this has settled the question of the non-authenticity of the discovery. But some still believe in it.