THE HOROLOGIUM
OF AUGUSTUS:
DEBATE AND CONTEXT
by
Lothar Haselberger
with contributions by
Paolo Albèri Auber, Géza Alföldy†, John Fillwalk, Bernard Frischer,
Robert Hannah, Peter J. Heslin, Eugenio La Rocca, Günter Leonhardt,
John Pollini with Nicholas Cipolla, and Michael Schütz
PORTSMOUTH, RHODE ISLAND
2014
JOURNAL OF
ROMAN
ARCHAEOLOGY®
JRA® SUPPLEMENTARY SERIES NUMBER 99
General Editor: J. H. Humphrey
Layout: C. Corey
ISBN-13: 978-0-9913730-3-1
ISSN 1063-4304 (for the supplementary series)
Copyright © 2014 Journal of Roman Archaeology, L.L.C.
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TABLE OF CONTENTS
Selected bibliography with abbreviations used in this book
Preface
7
13
The original debate (2011)
1. A debate on the Horologium of Augustus: controversy and clarifications (2011)
Lothar Haselberger
15
2. The Augustus Code: a response to L. Haselberger (2011)
Peter J. Heslin
39
3. The Horologium on the Campus Martius reconsidered (2011)
Michael Schütz
43
Expanding the debate
4. Observations on Augustus’ obelisk, meridian, and Ara Pacis, and their symbolic
significance in the Bildprogramm of Augustus
John Pollini with Nicholas Cipolla
53
5. Reconstructing Augustus’ Montecitorio obelisk: a gnomonist’s point of view
Paolo Albèri Auber
62
6. New digital simulation studies on the obelisk, meridian, and Ara Pacis of Augustus
Bernard Frischer and John Fillwalk
77
7. Ancient and modern gnomonics: concerns and clarifications
Michael Schütz
91
Broadening the context
8. Horologium and Mausoleum Augusti: an overview of the fieldwork (1979-97)
and the existing documentation (2013), with Addendum (2014)
Günter Leonhardt
101
9. The Horologium of Augustus as a sundial (2011), with Addendum (2013)
Robert Hannah
107
10. The Horologium of Augustus and its model at Alexandria (2011)
Géza Alföldy†
117
11. Augustus’ solar meridian and the Augustan urban program in the northern
Campus Martius: attempt at a holistic view
Eugenio La Rocca
121
Challenges and outlook
12. The ‘Horologium’: where do we stand, and where should we go?
Lothar Haselberger
167
Indices
203
Preface
The Horologium on Rome’s Campus Martius remains as controversial today as it was in
2011 when a collection of essays in the Journal of Roman Archaeology attempted to clarify the
points of contention. Notably, the range of different positions has since increased. Broad agreement exists only on one point: the debate surrounding Augustus’ colossal gnomon-obelisk
(re-erected in 1790-92 on Piazza Montecitorio) and its “wondrous function” (recorded by Pliny,
NH 36.71-73) cannot be brushed aside. Any treatment of Augustus, whose bimillennial we are
celebrating in 2014, and any study of imperial Rome, from visualizations of the material city
to questions of propaganda and Kaiserkult, would be deficient without an acknowledgement of
the Horologium, despite the intense debate surrounding it.
Inspired by the momentum created in 2011, and hoping to enter a new era of collaborative
investigation regarding the Augustan solar monument, I welcomed the editor’s offer to contextualize the articles collected at JRA 24 (2011) 47-98 within a collection of new essays for a
supplementary volume. G. Leonhardt, junior excavation architect of the Horologium fieldwork
during the years 1979-97, informs us about the unpublished documents left after E. Buchner
passed away in August 2011; they are now archived in the Kommission für Alte Geschichte und
Epigraphik (Munich) of the German Archaeological Institute (DAI). J. Pollini, together with
N. Cipolla, was the first to apply digital simulation technology to explore the Horologium; here,
they respond to critiques and explain the strategies, methods, and limitations of their approach.
P. Albèri Auber added a new archaeo-astronomical voice to the debate in 2012, when he postulated a precisely-calculated 100-foot height for the obelisk. In this volume, he presents a revised
version of his reconstruction of the gnomon-obelisk and now suggests two different phases of
an evolving Augustan building project; counter to the common opinion, he also proposes here
that the obelisk’s excavated meridian line is actually that described by Pliny and thus Augustan, rather than Flavian, in date. Accepting these hypotheses, B. Frischer and J. Fillwalk present
new digital simulations to model the Augustan obelisk, meridian, and Ara Pacis. These, in turn,
are challenged by M. Schütz. Willing to abandon his anonymity as a referee reader, he agreed
(upon my very late request) to detail his points of criticism, and to serve as a voice of warning
against the fictive realism of digital simulation. Moreover, he explains ancient calculation methods and on this basis questions the 100-foot gnomon proposed by Albèri Auber and adopted
by Frischer and Fillwalk. Finally, E. La Rocca situates the Augustan solar monument within
Augustus’ building program in the northern Campus Martius, outlining the grand imperial
vision laid down in the gnomon-obelisk and the monuments surrounding it.
A lively exchange of ideas has accompanied the creation of this volume, intended to encapsulate the state and spirit of the ‘Horologium’ debate. The intensity of collaboration and
last-minute dynamics in the preparation of this volume were thoroughly stimulating. My
gratitude extends to the authors who accepted the invitation to contribute to this volume and
endured the multiple revisions, shared readings, and adjustments of their manuscripts. My
thanks include the many helpful hands and minds (see below, 185) who contributed to gathering Buchner’s research material on the Horologium that had been deposited in various places
over the years. As late as June 2011, in what turned out to be my last visit to the hospitable home
of Edmund and Helga Buchner, we discussed strategies of editing and revising the Horologium documentation — which, alas, was not meant to come to fruition.1 Yet the momentum
was there, and consolidation of the archival material was essentially concluded in March 2013.
Helped by the momentum generated by the present volume, this will carry us forward, I trust,
into the next phase of investigating Augustus’ gigantic solar timepiece.
Lothar Haselberger
1
Philadelphia, May 2014
The memorial gathering in August 2012 in Berlin, at the anniversary of Buchner’s death on
August 27, 2011, is documented in Deutsches Archäologisches Institut (ed.), “Reden der
Gedenkfeier für Edmund Buchner,” AA 2012, 207-26; on the process of gathering the Horologium material, see ibid. 226 (C. Schuler).