The first eclipse canon, Elementa Eclipsium

These rare eclipse maps published in 1816 are available for purchase at

The first true canon of solar eclipses was developed in 1816 by the Moravian astronomer Cassian Hallaschka. A summary of Hallaschka’s achievements appears in Historical Eclipses in Europe by Susanne Débarbat:

“One remarkable book - Elementa eclipsium ... - was published in Prague in the year 1816 by Franz Ignaz Cassian Hallaschka (1780 - 1847). It contained the maps for eclipses between 1816 and 1860 and was followed by a second volume with maps of eclipses until 1910 (Solc, 1999). The geometric constructions used by Hallaschka anticipated the standard theory of eclipses developed later by Friedrich Wilhelm Bessel. In the introductory chapter, most of contemporary European authors of eclipse calculations are listed - Du Sejour, Monteiro, Goudin, Delambre, Wolf, Mayer and other authors of eclipse papers like Euler, Lalande, T. Mayer, Lagrange, Lexell, Cagnoli, Gerstner, Kluegel and Bohnenberger. However, Hallaschka developed his own method determining the umbral size and position according to the work of Cl. Wurm and geometric projections on the Earth’s surface were based on the books by Lalande and Rüdinger.”

The Elementa Eclipsium gives both a new theory of eclipse calculation and a comprehensive series of eclipse maps that applies Hallaschka’s new theory of eclipses. It is a broad work -- covering a span of seven decades in all, written in Latin, and with orthographic projections of the entire path of eclipses -- but Elementa Eclipsium also has a parochial quality as manifested with these characteristics:

• Only solar eclipses in which Brno (a city in the present-day Czech Republic) lies within the region of partial eclipse (penumbra) appear in the Elementa Eclipsium.

• Figures of the eclipse’s appearance during maximum eclipse are given for the perspective of Brno.

Eclipse timings are given for Brno.