d _United States National Museum Bulletin_.

In these series, the Museum publishes original articles and
monographs dealing with the collections and work of its constituent
museums--The Museum of Natural History and the Museum of History and
Technology--setting forth newly acquired facts in the fields of
anthropology, biology, history, geology, and technology. Copies of each
publication are distributed to libraries, to cultural and scientific
organizations, and to specialists and others interested in the different
subjects.

The _Proceedings_, begun in 1878, are intended for the publication, in
separate form, of shorter papers from the Museum of Natural History.
These are gathered in volumes, octavo in size, with the publication date
of each paper recorded in the table of contents of the volume.

In the _Bulletin_ series, the first of which was issued in 1875, appear
longer, separate publications consisting of monographs (occasionally in
several parts) and volumes in which are collected works on related
subjects. _Bulletins_ are either octavo or quarto in size, depending on
the needs of the presentation. Since 1902 papers relating to the
botanical collections of the Museum of Natural History have been
published in the _Bulletin_ series under the heading _Contributions from
the United States National Herbarium_, and since 1959, in _Bulletins_
titled "Contributions from the Museum of History and Technology," have
been gathered shorter papers relating to the collections and research of
that Museum.

The present collection of Contributions, Papers 34-44, comprises
Bulletin 240. Each of these papers has been previously published in
separate form. The year of publication is shown on the last page of each
paper.

FRANK A. TAYLOR
_Director, United States National Museum_

* * * * *

Contributions from the Museum of History and Technology:
Paper 35

THE BORGHESI ASTRONOMICAL CLOCK
IN THE MUSEUM OF HISTORY AND TECHNOLOGY

by

SILVIO A. BEDINI

DEVELOPMENT OF ASTRONOMICAL CLOCKS 32

DESIGNER BORGHESI 33

CLOCKMAKER BERTOLLA 34

FIRST BORGHESI CLOCK 38

SECOND BORGHESI CLOCK 41

BORGHESIAN THEORY OF THE UNIVERSE 54

LAST YEARS 57

THE CLOCKS OF BARTOLOMEO ANTONIO BERTO