September 2001 page 111
David W. Hughes

Book Review - "The Universe Unveiled. Instruments and Images through History"

A review of "The Universe Unveiled. Instruments and Images through History", based on the Adler Planetarium"s collection. The book showcases historical astronomical instruments and illustrations, explaining how they contributed to understanding celestial movements. The reviewer praises the book's stunning visuals and engaging narrative, recommending it as an introduction to the history of post-Copernican astronomy.
Dials: Astrolabe, Book Reviews, Historical Dials

October 1993 page 8
David W. Hughes

An Introduction to the Equation of Time

This article explains the Equation of Time, the difference between local apparent solar time (sundial time) and mean solar time (clock time). It details the two astronomical reasons for this variation: Earth's elliptical orbit causing the Sun's speed to change, and the Sun's apparent motion along the ecliptic rather than the celestial equator.
Equation of Time, Mathematics of Dialling