This article focuses on the additional informational elements, or "furniture," found on vertical sundials beyond just hour lines. It uses the Queens' College dial as an example of a dial rich in such information (altitude, azimuth, zodiac, sunrise time, day length). The author explains how to calculate and display various furniture types, including equinox and solstice declination lines, altitude and azimuth lines, and monthly declination lines, all based on the shadow cast by a "nodus" on the dial. The methodology involves transforming the vertical dial to an equivalent horizontal dial for simplified calculations and discusses the practical aspects of displaying such data.
Dials: Vertical,
Mathematics of Dialling,
Sundial Design & Layout