Gimblet walked slowly along the lawn at the edge of the bed, his eyes on the black peaty mould, where it was visible among the flowers. About twenty yards from the hedge, he stopped with a muffled exclamation. The bed in front of him was covered with footprints of all shapes and sizes; but plainly distinguishable among the rest were the neat nail-encrusted marks which matched the boot he held in his hand. He put it down on the ground and carefully made an imprint with it in the soil, beside the existing footmarks. It was easy to single out its fellows.
"Two extra nails," murmured Gimblet to himself, "but otherwise, the same. Probably made on the same last."
Stepping cautiously in the places where his predecessors had walked, he followed the tracks that had betrayed Sir David Southern. They were numerous and distinct; he counted fourteen of each separate foot. First Sir David would seem to have walked straight across the bed, then returned and taken up his position near the middle. He was not contented with that, it seemed, for he had walked backwards five or six paces and then moved sideways again till he was exactly opposite the opening between the curtains. Here the ground was trampled down as if he had several times shifted slightly from one place to another. Whether or not he was exactly in line with the writing-table Gimblet could not see, as its position was hidden in the obscurity behind the drawn curtains. It would want a light there to prove that, thought Gimblet; still there was no reason to doubt that it was so. There were four or five more footmarks leading back to the lawn, and over these Gimblet stooped with particular interest.
With a tape measure, which he took from his pocket, he measured the distances between the prints, entering the various figures in his notebook, beside carefully drawn diagrams. Then he picked his way to the edge of the lawn, and stood a moment considering.
Apparently he was not satisfied, for presently he retraced his steps delicately to the middle of the bed, till he was once more just behind the place where the earth was trodden down. After pausing there an instant, he turned once more, and ran quickly back to the grass, without this time troubling himself to step in the chain of footprints used previously by the police. But he had not even yet finished; and was soon crouching down again, with the tape measure in one hand and the notebook in the other, poring over the evidence preserved so carefully by the impartial soil.