A’s nephew has absconded from his home. He sent his servant to trace his missing nephew. When the servant had left,A then announced that anybody who discovers the missing boy would be rewarded. When the servant came to know about the reward, he brought an action against A to recover the same. But his action failed. It was held that the servant was not entitled to the reward because he did not know about the offer when he discovered the missing boy. Name the case on reading the facts.