571. The common Acacia, or American locust-tree, is a native of the mountains of America from Canada to Carolina. It is a beautiful tree, attains a considerable size, and is of very quick growth. According to Hassenfratz, the mean size of its trunk is 32 feet in length and 23 inches diameter.

The wood is much valued for its durability. Some of the houses built by the first settlers in New England of this wood still continue firm and sound; and in posts, stakes, and pales it is found to be one. of the most durable kinds. It is adapted for any purpose to which oak is applied. It makes excellent treenails for ships, and is valuable for fencing. There are several other species, but we have specimens only of the kind now described.

The colour of the wood of the acacia is of a greenish yellow, with a slight tinge of red in the pores. Its structure is alternately, nearly compact, and very porous, which marks distinctly the annual rings. It has no large rays, and therefore no flowered grain. It has no sensible taste or odour in a dry state. About the same degree of labour is required to work it that ash requires.

The cohesive orce of a square inch varies from 10,000 to 13,000 lbs.; and the weight of a cubic foot when seasoned is from 49 to 56 lbs. Its other properties, determined from young wood in an unseasoned state, are as under: -

Weight of the modulus of elasticity for a square inch, 1,687,500 lbs.

Hence in a dry state it would probably bo superior to oak in these properties.