’ dedication to this work extended to him cutting out and colouring each part of every volvelle himself. Fabulously expensive to produce and prohibitively expensive to buy, it was always a rare book. Nicholas Wotton reported in 1544 from the 'Diet of Speyer' that Apianus would give Henry VIII a copy, for otherwise the king would not be able to get hold of it; Edmund Halley tried in vain to obtain a copy.

‘Astronomicum Caesareum’ is divided into two parts. The first includes forty chapters with volvelles reproducing the position and the movement of celestial bodies, including the Sun, Moon, and planets. The second part describes the meteroscope, an instrument designed to solve problems in spherical trigonometry, and relates the sighting of five comets. 

The volvelles in the work are each placed within a frame reminiscent of an astrolabe, a contemporary device that modelled the movement of the Heavens in two dimensions and enabled the calculation of time and place and assisted with astrology. The first moveable woodcut, which represents the planispheric astrolabe, compresses both hemispheres onto one plate. According to the text, the plate depicts 1,033 stars, and was based on the first printed star charts published in 1515 by 

.

The most spectacular of the volvelles, which are the work of the artist Michael Ostendorfer, are the dragon plates. These include the title- page and the double-page spread dragon and moon dials. The dragon dial can be used to calculate the nodes of the Moon, the two points of intersection between the yearly path of the Sun, and the plane of the lunar orbit, which produce eclipses. Dragons were associated with eclipses, which were believed to occur when their head or tail blocked the Sun. The thirteen small dragons indicate different parts of the lunar cycle.

 (1495–1552) studied at the University of Leipzig from 1516 to 1519, where he adopted the Latinised version of his German name. In 1519, he moved to Vienna, where he was part of the second Vienna School of 

, which included Georgius Tannstetter and Johannes Cuspinianus. He then moved again to Landshut, where he produced the ‘Cosmographicus Liber’ in 1524, an extremely popular work on astronomy and navigation that was reprinted thirty times. He was later appointed printer at the University of Ingolstadt and eventually to Charles V, Holy Roman Emperor to whom Apianus dedicated his most famous work, ‘Astronomicum Caesareum’, in 1540.

Apianus worked on the project for eight years prior to publication, which he issued from his private press at Ingolstadt. ‘Astronomicum Caesareum’ (‘

 of the Caesars’) is a comprehensive review of contemporary astronomical knowledge, ranging from the use of solar eclipses to determine longitude to Apianus’s own observation that the tails of comets always point away from the sun. The work is beautifully illustrated and crammed with intricate volvelles, which could be used to calculate everything from eclipses to the hour of a baby’s conception. Apianus continued to work in Ingolstadt until his death, teaching relatively little but producing work on sines, a variation on Pascal’s triangle and manuals for horological instruments.


This pioneering textbook on astronomy was produced by 

, astronomer and professor of mathematics at Ingolstadt, and dedicated to the Holy Roman Emperor Charls V and his brother Ferdinand. It contains a comprehensive review of contemporary astronomical knowledge, including theories from the use of solar eclipses to determine longitude and Apianus' own observation that the tails of comets always point away from the Sun. 

The work is beautifully illustrated and full of intricate volvelles, hand coloured by Apianus. These circular devices could be used to calculate everything from eclipses to the hour of a baby’s conception. Only thirty-five copies of this iconic work are known. This copy preserves many of the silk threads used for turning the volvelles, including twelve of the original seed pearls placed at the end of the threads.

In dedicating his work to Charles V and his brother Ferdinand, the two ‘Caesars’ of the title, 

 secured important patronage for his luxurious work of science. Throughout the work, his calculations are based on the birth dates of the brothers. Apianus observed and meticulously recorded, in the second part of his work, the passage of five comets, including that which would later be named Halley's comet. He illustrates the phenomenon that the comets' tails always trail away from the sun, a tantalising clue as to the heliocentric nature of the universe. In spite of this, Apianus's work describes a geocentric universe, just three years before Nicolaus Copernicus's revolutionary description of the true nature of our heliocentric Universe was published as 'De Revolutionibus' (1542). 

Double volvelle spread

Frontispiece

Dedication page with coat of arms

Zodiac, Constellations

Volvelle

Saturn's orbit

Latitude of Saturn Volvelle

Jupiter's orbit

Jupiter Volvelle

Mars' orbit

Latitude of Mars Volvelle

Movement of the Sun

Movement of Venus

Latitude of Venus Volvelle

Mercury's orbit

Latitude of Mercury Volvelle

Volvelle with the zodiac 

Lunar volvelle

Volvelle to calculate when the moon reaches its apex

Lunar calculation volvelle

Moon volvelle

Volvelle for predicting lunar eclipses 

Eclipses of the sun and moon

Sun volvelle

Moon volvelle 2

Magnitude volvelle

Volvelle for planetary conjunctions

Volvelle for planetary conjunctions 2

Planetary movements volvelle

The Golden Number volvelle

Dominical letter volvelle

Calendar volvelle

Horoscope volvelle

Movement of the Moon in relation to the Sun

A pristine copy with distinguished provenance of 

 of the Caesars’  – an important work to the history of science, astronomy, and computing. One of only about thirty-five examples printed, each decorated with pearls, hand-coloured by Apianus himself.

Folio. Titlepage framed by a woodcut border, on verso of the same leaf woodcut coat of arms of joint the dedicatees Charles V and his brother Ferdinand of Spain. 53 eleven-line and 39 six-line historiated woodcut initials by Hans Brosamer; 36 full-page woodcut astronomical figures coloured by a contemporary hand, of which 21 have a total of 83 volvelles [complete]; 44 silk threads [complete]; and 12 pearls [complete]; full-page woodcut arms of the author by Michael Ostendorfer on folio O6. 

Apianus’s ‘Astronomy of the Caesars’