William Watson describes a new instrument for finding a meridian line to aid in sundial making, using two tubes aligned with Polaris and Capella. Michael Lowne comments on the necessity of accounting for Polaris's displacement from the true pole and the stars' right ascension difference for correct alignment, noting potential inaccuracies in Watson's original design and challenges in its use.
How Sundials Work,
Mathematics of Dialling,
Dialling Tools