Why bother to correct a Sundial
.... there are two schools of thought. Those who think that solar time is true time. And those who think a sundial should aim to supply some indication of civil time.
Equiangular Dial Introduction
.... some general background on equiangular dials.
Curved Hour Lines Sundials
.... covering sundials with full analalemma, half analemmas, noon marks and spider dials
Moving Hour Lines Sundials
.... dials using Moving Hour Lines are usually equatorial, e.g. the Chartres dial. But there are exceptions.
Shaped Style Sundials
.... dials where the shape of the style offsets the Sun's shadow to compensate for the Equation of Time & Longitude Correction.
Moving Style Sundials
.... analemmatic dials, Forster-Lambert and similar moving style dials that have equiangular hour lines can be corrected to civil time using the Pilkington or similar method.
Sundials with Alidades
.... dials with a moving 'sight' mechanism, usually incorporating an analemma.
.... bifilar dials with north/south east/west threads have equiangular hour lines : thus can be corrected to civil time, using e.g. the Pilkington method.