Note 481 — Chapter IV
Walter Armstrong translation
We have already mentioned the size of its steps; see page 192. The gradient for the first stage was about one in twenty. In the upper stages it must have been far steeper, as the circumference of the stages was much less, while their height remained the same. It never became very abrupt however, as supposing that the original number of stories was seven, the gradient would not be more than about one in fourteen close to the summit.