In answer to your query with reference to Yellow and Black Locust, I would state that there are two varieties. The Yellow Locust is erect in growth, has very thin sap-wood, is very durable, and of smooth cleavage. A gate-post, set to my knowledge in 1801, is as sound to-day as a " trade dollar".

Black Locust is irregular in growth, nearly as much so as Catalpa, is rough in cleavage, has darker wood, and is not so durable as the Yellow variety, and has thick sap wood even when mature.

Yellow Locust is harder and more durable, but not so tough as the Black variety. The difference does not arise from soil or situation, as both grow in the same groves here. I shall at an early day send you sections of wood from each, and in the meantime try to determine other specific differences.