What is a tine, prong, or fork. Specifically: (a) One the branches of a valley or of a river. (b) pl. An iron first speak or harpoon, having four or more barbed points called?

grain — A tine, prong, or fork. Specifically: (a) One the branches of a valley or of a river. (b) pl. An iron first speak or harpoon, having four or more barbed points. (Webster's 1913.)