It is certain that some rhinoceroses have but one horn, and others have two; but it is not equally certain that this variety is constant, and depends on the climate of Africa or India, or that two distinct species may be established from these differences. It seems that the rhinoceroses with one horn have it bigger and longer than those who have two. There are single horns of three feet and a half, and, perhaps, of more than four feet in length, by six, or seven inches in diameter at the base. Some double horns are but two feet in length. Commonly these horns are brown, or olive colour, though some are grey, and even white. They have only a small concavity, in form of a cup, under their base, by which they are fastened to the skin of the nose; the remaining part of the horn is solid, and very hard. It is with this weapon that the rhinoceros is said to attack, and sometimes mortally wound, the biggest elephants, whose long legs give the rhinoceros an opportunity of striking them with his snout and horn under their bellies, where the skin is tender, and penetrable; but if he misses the first blow the elephant throws him on the ground and kills him. The horn of the rhinoceros is more valued by the Indians than the ivory of the elephant, not so much on account of its real use, though they make several things of it with the chisel, but for divers specific virtues, and medicinal properties, which they ascribe to it. The white, from being the most rare, are also those which they value most. Among the presents which the king of Siam sent to Louis XIV. in 1686, were six horns of the rhinoceros. We have seen in the king's cabinet twelve of different sizes, and one of them, though mutilated, is three feet eight inches and a half in length.