Tom watched patiently all day, but, with the exception of a boy in charge of some goats, no one went near the spring, and the boy did not go within a hundred yards of it, though his goats were feeding all round and close to it.
"Glad to see you back, Burton," exclaimed Tom when he returned to camp and found the officer there.
"What luck, Tom?" asked the Doctor.
"Bad. I waited until it was too dark to see, and the message had not been taken when I came away," he replied.
"You are wrong, Tom, my boy, for I saw it taken," said Burton.
"How? Where were you?" asked Tom, in surprise.
"Not far from you, and I saw a goat sniff it and quickly walk off with the paper in its mouth, and five minutes later the boy had it in his hand. Here, smell this," and Burton held out the paper containing the message to the Doctor.
"A peculiar smell," said Tom.
"Yes, and the goat is trained to carry anything impregnated with that subtle odour," explained Burton.
"Do you believe the writer of this knows where Mark is, Burton? Have you discovered anything?" asked Tom.