It was a bushmaster which started the Quest of the Emerald-and only a possible bushmaster at that. One May evening in Cornwall, Big Jim Donegan, the lumber-king, sat in the misty moonlight with his slippered feet on the rail of the veranda of the great house in which he lived alone. He was puffing away at a corn-cob pipe as placidly as if he did not have more millions than Cornwall has hills-which is saying something, for Cornwall has twenty-seven of the latter.