The book opens with a foundational view of practical astronomy during the eighteenth century, contrasting the Greenwich tradition of exact measurement with the speculative boldness of the early French geometers. It examines the career of Sir William Herschel, whose pioneering sweeps of the heavens revealed the dynamic, evolving nature of stars, double systems, and nebulæ. The narrative then shifts to the rigorous German school led by Bessel, detailing the systematic reduction of observations, the elimination of instrumental errors, and the determination of stellar parallaxes and proper motions.
The work explores the persistent attempts to solve the problem of stellar distance, culminating in the successful measurement of 61 Cygni, Vega, and Alpha Centauri. It investigates the growing understanding of solar phenomena, detailing the evolution of ideas regarding sun-spots and the critical role of total solar eclipses in revealing the corona and the chromosphere. The text traces the theoretical prediction and subsequent optical discovery of Neptune, alongside the search for minor planets in the vast gap between Mars and Jupiter.
The development of cometary astronomy occupies a central place, detailing the calculation of periodic orbits, the discovery of short-period comets, and the physical anomalies of cometary tails. The narrative also examines the immense improvements in telescopic power, from the giant reflectors of Herschel and Lord Rosse to the precision refractors of Fraunhofer and Merz. The volume concludes by surveying the expansion of the astronomical horizon and the unification of physical sciences that laid the groundwork for modern astrophysics.
