“Plaster of Paris gives a rotten result if you try to take casts of sand-impressions with it,” he explained. “The classics pass rather lightly over the point, but it is so. Therefore we turn to melted wax or tallow, and by dropping it on very carefully in a thin layer at first, we get something that will serve our purpose. Hence the candles and the blow-lamp. See?”
He suited the action to the word, making casts of the right and left footprints in the sand from the sharpest impressions he could pick out.
“Now we'll take Mr. Billingford's track next,” he said, as he removed the two blocks of wax from their beds. “His footmarks will be the first to be swamped by the tide, so we must get on to them in a hurry.”
He led his companions back to the road and turned round the landward end of the groyne.
“This is where he landed on the road, evidently. Now step in my tracks and don't wander off the line. We mustn't cut up the ground.”
He moved along the trail, and soon reached the tidal mark, after which the footprints grew sharper. A little farther on, he reached a point where Billingford's marks crossed an earlier track—the prints of a woman's nail-studded shoes.
“Golfing-shoes, by the look of them,” he pointed out to his companions. “We can leave them alone just now. The tide won't reach here for long enough yet, so we've plenty of time to come back. Billingford's the important thing at present.”
Billingford's track ran down to Neptune's Seat, where it was lost on the hard surface of the rock. Sir Clinton, without halting, directed his companions' attention to a second trail of male footprints running up towards the rock from the road, and crossed just at the landward side of Neptune's Seat by the traces of Billingford.
“There's no return track for these, so far as I can see,” he pointed out, “so it looks as if the murdered man made them.”
Without a glance at the body, he stepped up on to the rock, picked up the farther trail of Billingford, and began to follow it as it led along the beach towards Lynden Sands village. The footprints ran along the top of a series of slight whale-backs of sand, behind which lay a flatter zone running up towards the high-tide mark. Nearer the sea, a track showed the inspector's line of advance during the night. After following the trail for nearly a quarter of a mile, Sir Clinton pointed to a change in its character.