He had completed his work and was about to retire disappointed when the presence of a small scrap of yellow clay which he had observed on entering, but to which he had given no attention, suddenly struck him as being slightly puzzling. It was shaped like a half-moon, the inner edge showing a definite curve. Evidently it had caked round a man’s heel and had dropped off, possibly as the heel had become drier in the shed. French looked round and presently he saw two more pieces. One was stuck to the rim of the left wheel of the handcart as if the wheel had rolled over a clod and picked it up, the other was on the left leg as if the leg had been put down on a similar clod which had stuck in the same way. It was, of course, evident that the handcart had been not only wheeled over a place where there was yellow clay, but had been set down there. At first French saw nothing remarkable in this, but now it occurred to him that he had not noticed any clay of the colour in the neighbourhood. Where then had the pieces been picked up? He had seen similar clay on the previous night, but not close by. The heap of stuff removed in opening the grave down in Thirsby was just that kind of material. He had noticed it particularly in the light of the acetylene lamp. It was of a characteristic light yellow and very stiff and compact like puddle. But he had seen nothing like it up on the moor. The soil all about was dark coloured, almost peaty. He cast his thoughts back to that scene in the graveyard and then he recalled another point. He had looked down into the grave when the coffin was being raised, and he now remembered that the sides of the opening had shown black soil over the clay. A layer of some three feet six or four feet of dark, peaty soil had covered the yellow. French whistled softly as the possible inference struck him. A worn but still serviceable looking spade stood in the corner of the shed. French picked it up, and going a few yards out on to the moor, began to dig. He was not particularly expert, and before he had worked for many minutes he was in bath of perspiration. But he persevered and the hole grew until at a depth of nearly three feet he found what he wanted. The spade brought up a piece of hard, compact clay of a light yellow colour. French had grown keenly interested as he filled in the hole and removed the traces of his work. With a feeling of suppressed excitement he returned to the shed and carefully packed the half-moon shaped cake of clay in a matchbox. Then locking the door, he went out again on the moor and stood looking round him as he pondered the facts he had just learned.