The height of mountains philosophically considered is properly computed from the surface of the next sea; but as it affects the eye or imagination of the passenger, as it makes either a spectacle or an obstruction, it must be reckoned from the place where the rise begins to make a considerable angle with the plain. In extensive continents the land may, by gradual elevation, attain great height, without any other appearance than that of a plane gently inclined, and if a hill placed upon such raised ground be described, as having its altitude equal to the whole space above the sea, the representation will be fallacious.
These mountains may be properly enough measured from the inland base; for it is not much above the sea. As we advanced at evening towards the western coast, I did not observe the declivity to be greaterthan
