The preceding section shall not be construed to prevent a person from going across any watercourse in his own boat, or taking therein his own property, or the members of his own family, or persons in his employment; nor to prevent a merchant or miller from carrying across a watercourse in his own boat, without reward therefor, any person bona fide engaged in the actual transportation to or from his store, mine, or mill, of grain, coal, timber or other produce.