The title of this work is: The letters of Baron Francis X. Zach, Director of the Observatory of Gotha-Seeberg, and his successors Bernard von Lindenau to Father Martin Alois David, Assistant Astronomer and Director of the Royal Observatory of Prague from 1791 till 1816. The study contains a) 62 letters of Zach, b) 9 letters of Lindenau, all of them being of astronomical interest and kept in the records of the Observatory of Prague (IV.), and c) notes of David (III.) as they were written during his visit at Zach 1789 and 1801. - In his introduction, the editor follows the personal and literary contacts of David with Zach (I.). The statistics of the correspondence (II.) reports on a) the letters published in the work, b) on the letters of Zach and Lindenau mentioned only in David´s diaries or partly published in the reviews on account of their scientific value, an c) on a list of letters of David sent to Zach and Lindenau that have nor been found till today, being known from David´s diaries only. In the V. part there is a list of essays written by David and Adam Bittner. Assistant Astronomer of Prague Observatory, which were published in reviews edited by Zach and Lindenau, and a list of Zach´s reports on David´s essays.
The distribution of stars of mag. 7-0 and brighter of the H. D. C. is here studied in the system of galatic co-ordinates. There are tables of numbers of stars according to both the co-ordinates for individual clases of magnitude and for all the spectral subdivisions. Also the distribution of the density of stars in longitude and latitude separately is studied for the spectral classes B, A, F, G, K, M. Finally to illustrate the distribution of stellar density according to both co-ordinates simultaneously, the maps for the classes B, A, F, G, K, M were constructed with the lines of the same density. and Text je doplněn 5 grafy hustoty hvězd (nestránkováno)