Just after the middle of the 18th century, the subject of astronomical clocks suddenly became a major horological preoccupation in another region, namely, Austria, where the work in this field was apparently done exclusively by members of the clergy. The earliest was Father Philipp Matthäus Hahn (1739-1790) of Württemberg.[4] Father Hahn considered the equation of time as only one part of a plan to represent astronomical occurrences by means of clockwork. In addition to planetaria and similar mechanisms, Father Hahn produced two extraordinary astronomical, tall-case clocks, both of which survive in public museums.
The author wishes to acknowledge the valuable assistance received from the following: DR. AMOS AVERY, Amherst, Massachusetts; MR. EDWIN A. BATTISON, curator of light machinery and horology, U.S. National Museum; DOTT. RICHARD BLAAS, Oesterreiches Staatsarchiv, Vienna; DOTT. ADOLFO CETTO, librarian, Biblioteca Comunale di Trento, who made copies of Borghesi's two volumes available; SIGNOR MARIO DI MARIO, editor of _La Clessidra_, Rome, who permitted several of the illustrations in Sig. Luigi Pippa's article to be used herein; MR. WALTER A. GILBERT, Norwich, Connecticut; DR. HEINRICH LINARDI, Uhrenmuseum der Stadt Wien, Vienna; SIGNOR LUIGI PIPPA, Milan, Italy; CAV. ING. GUIDO UCELLI DI NEMI, Presidente, and DOTT. FEDERICO MORELLI and CAV. ORAZIO CURTI of the Museo Nazionale della Scienza e della Tecnica, Milan, for their cooperation on the descriptions and illustrations of the restored clockshop of Bartolomeo Antonio Bertolla; and DR. EDWARD WATERS, Division of Music, Library of Congress, Washington, D.C.
The translation from Francesco Borghesi's Latin texts, which made this study possible, were made by: REV. NEIL HERLIHY, S.J., REV. FRANCIS J. HEYDEN, S.J., and REV. STEPHEN X. WINTERS, S.J., Georgetown University, Washington, D.C.; and REV. DANIEL HUNTER, O.P., and REV. ROBERT STENGER, O.P., Dominican House of Studies, Washington, D.C.
[Illustration: Figure 2.--PORTRAIT OF FATHER FRANCESCO BORGHESI, inventor and designer of the astronomical clock in the Museum of History and Technology.]
Another of the clerical clockmakers was Father Aurelianus à San Daniele (1728-1782), an Augustine monk in the monastery of the Imperial Court at Vienna.[5] His four complicated astronomical clocks, which exist in museums at present, are comparable to those produced by Father Hahn. The third cleric was Brother David à San Cajetano (1736-1796) in the same Augustine order to which Father Aurelianus belonged. He achieved note as the author of various publications, including _Neue Rädergebäude_[6] [New Construction of Wheels] relating to planet-wheels, or gear-trains containing epicyclic elements. He constructed a clock based on an elaborate astronomical design which was substantially different from the others. The fourth of the ecclesiasts who designed astronomical clocks in this period was Father Klein of Prague, who produced a complicated astronomical timepiece in about 1738.