On the way， Svend repeats again and again the name of what they are going to look for. So， by the time they arrive， Rolf is ready to get to work. He circles， backtracks and circles again. This he continues until he picks up the faint scent of an object lying in a spot where it doesn' t belong.
One spring I went to Funen to make sure that Rolf' s detective work was not some kind of fairy story. Over coffee and cakes Svend and I talked and watched Rolf. The dog' s stare was mysterious. He seemed alert yet calm. The telephone rang， and then I heard Svend saying， "A wallet？ I can' t promise， but we' ll do our best."
An hour later we were in a park， tramping among the trees with Axel Jensen， the man who had phoned. Jensen had lost his Wallet.
For half an hour Rolf roamed in wide， broken zigzags. Occasionally， Svend would call him back or tell him to keep looking. No wallet was found.
We drove to another part of the forest. Again Rolf roamed with his nose to the boggy earth. Svend encourage him from time to time. I don' t know at what moment we began to notice that Rolf was padding about in small circles. Svend was now standing at the edge of a ditch. He was tense， as if giving orders that only Rolf could hear.
Suddenly， Rolf began to paw the soft earth. He stopped， looked about and scratched again a few feet away. Then he changed his mind and began to dig further to the right. All at once he trotted out of the bog， head high. He was holding something dark in his mouth. It was the wallet！Jensen roared with surprise and joy.
"Tell me， Svend，" I said later， "how on earth does a dog go about finding a wallet five by seven inches in a huge forest covered with undergrowth？"
Svend smiled as he replied， "I knew there was nothing in the first 75 acres because of Rolf' s lack of interest. But in the swamp I could tell from the way Rolf acted that he had picked up a trail. The scent had reached him through the air from the spot where the wallet was dropped ten days ago."