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Rezension von Paolo Brenni: Building the World’s Best Telescopes in BavariaWissenschaftlicher Instrumentenbau der Firma Merz in München (1838–1932). Jürgen Kost (Tredition, Hamburg, 2015). Pp. 620. € 54. ISBN 9783732328857.
This ponderous work by Jürgen Kost is the first detailed and modern history of the famous Bavarian instrument firm Merz, active for nearly a century and for several decades in the nineteenth century one of the most important makers of large refractors, astronomical objectives, and optical instruments. This book is divided into two parts. The first retraces the development of the firm, and illustrates the activities and role of its owners from Georg Merz to Paul Zschokke. The second part offers a detailed descriptive and illustrated list of about 90 large refractors and 100 large objective lenses made by Merz. An appendix presents a bibliography and various documents related to the activity of the firm. Kost begins with the intricate history of collaboration among Georg Reichenbach, Joseph Utzschneider, Joseph Liebherr, and Joseph von Fraunhofer and their Bavarian workshops. In 1819, Utzschneider and Fraunhofer were partners in their Munich optical institute; they produced their optical glass in Benediktbeuern. When Fraunhofer died in 1826 at the age of 39, Utzschneider had the difficult task of finding his successor. Despite a very short career, Fraunhofer had been the mastermind as well as the emblem of the workshop. He enjoyed international renown, and his instruments were considered among the best of his time. Furthermore, Fraunhofer knew the secrets of optical glass making, a technology he had developed and refined together with the Swiss glass maker Paul Guinand. After much hesitation, considering several possible candidates, Utzschneider finally chose Georg Merz, who had worked in the institute since 1808 as “first optician”, and Gustav Mahler, who had worked at the institute since 1820 as chief of the mechanics workshop. In 1829, Merz and Mahler successfully completed the Königsberger heliometer (aperture 16.2 cm), and in 1835 the Bogenhausen (München) refractors (aperture 28.3 cm). In 1839, Merz and Mahler became full owners. In the following years, they made some very important instruments, including the large refractor for the Pulkowa observatory (aperture 38 cm). Mahler died in 1845, and Merz became the sole owner of the institute. Georg’s youngest son Sigmund had began to work with him in 1842, and around 1845 the firm became G. Merz & Sohn. Sigmund’s brother Ludwig also collaborated with the firm, mostly as a representative for the business abroad, but his role in the company was less important than Sigmund’s. Between 1829 and the 1880s, the firm was a world leader in the construction of large telescopes and objectives, and equipped most of the important astronomical observatories of the time. On the other hand, their development of photographic objectives and cameras was not particularly successful. Georg died in 1867 and Sigmund owned the firm until 1883 when he retired and donated it to the sons of a younger brother of Georg. Meanwhile, competition from other European and American makers of large refractors (Grubb, Gautier, Clark, Warner and Swasey, Repsold, Steinheil, etc.) as well as from producers of optical glass (Feil, Chance, Schott) grew ever stronger, and thus, Merz lost the predominant market it had held for half a century. Finally in 1903, the instrument maker Paul Zschokke purchased the firm but retained the name G. & S. Merz. A particularly interesting instrument invented by L. Schupmann and developed and sold by Zschokke was the “medial-telescope.” Its objective was made of a single lens of crown, with correction made by two concavo-convex lens and a concave mirror set after the focus of the objective. Not requiring a large flint lens, the medial telescope gave a better correction of the secondary spectrum. Nevertheless, only a few instruments of this type were sold; the medial telescope never captured the favour of professional astronomers. With Zschokke’s death in 1932, the saga of the famous optical institute came to a definitive end. The second part of this book provides a 150-page inventory of the most important objectives, refractors, heliometers, comet seekers, and medial telescopes made by the firm. For each instrument, the maker’s precise name, customer’s name, dates of order and delivery, key technical data (aperture and focal length), and price, followed by brief descriptions of the instrument’s subsequent history, are listed. Many photos or engravings are included. Unfortunately, it is not always possible to understand whether an instrument is still extant. An appendix includes a bibliography, list of the firm’s catalogues published between 1811 and 1930, list of the glass smeltings completed at Benediktbeuern between 1842 and 1885, and facsimile reproduction of three Merz catalogues for 1832, 1878, and 1900. The bibliography is certainly ample, but the author appears to have focused on primary biographical sources and less on the secondary sources. This book was accepted as a doctoral dissertation at the University of Hamburg in 2014. Much of the existing literature on the history of nineteenth-century German instrumental optics focuses on achievements of Fraunhofer, who has become a kind of mythical father of modern optics. Certainly, his role in the development of this science, in optical glass and instrument making cannot be overestimated. Nevertheless, the premature death of Fraunhofer did not finish off the Munich optical institute. Kost clearly demonstrates how Georg Merz and his successors were able not only to continue Fraunhofer’s tradition of excellence but also to increase the range of their products and to become for several decades the world’s most important and appreciated maker of large telescopes and large objectives. This book thus casts a new light on the history of the Merz firm primarily by analysing, for the first time, correspondence and other archival documents related to the business and to the management of the company (see also Ivo Schneider’s richly documented book on Utzschneider, published in 2014). Kost’s volume will be an essential working tool and an invaluable source of information for historians of optics, optical instruments, instrumental astronomy, and precision industry in the nineteenth and early twentieth centuries. Paolo Brenni CNR, Fondazione Scienza e Tecnica p.brenni@museogalileo.it