We may not arrive at our port within a calculable period, but we would preserve the true course.
While polysymmetry is solely conditioned by the manner in which the mimetic twin is built up from the single crystals, there being no change in the scalar properties, and the vector properties being calculable from the nature of the twinning, in the case of polymorphism entirely different structures present themselves, both scalar and vector properties being altered; and, in the present state of our knowledge, it is impossible to foretell the characters of a polymorphous modification.
Koenig constructed a series of bars forming a harmonicon, the frequency of each bar being calculable, and he found the limit to be between 16,000 and 24,000.
Hence to give a margin of safety to cover contingencies not calculable, an excess of material must be provided.
On the Copernican change the heavenly bodies were recognized as concrete and yet subject to calculable law.