(i.)
The error of scale along any parallel (near the centre), of which the co-latitude is b is
1 − { h (z + b) / sin b }.
(ii.)
This is a maximum when
tan b − b = z, whence b is found.
Also
| 1 − | h (z + b) | = | h (z + c) | − 1 whence h is found. |
| sin b | sin c |
(iii.)
For the errorless parallels of co-latitudes γ and γ′ we have