5. The pitch of the voice is likewise different and varying in quality with different nations, for the following reasons. The terminating points east and west on the level of the earth, where the upper and lower parts of the heaven are divided, seem to lie in a naturally balanced circle which mathematicians call the Horizon. Keeping this idea definitely in mind, if we imagine a
line drawn from the northern side of the circumference (N) to the side which lies above the southern half of the axis (S), and from here another line obliquely up to the pivot at the summit, beyond the stars composing the Great Bear (the pole star P), we shall doubtless see that we have in the heaven a triangular figure like that the musical instrument which the Greeks call the “sambuca.”
