Displaying astrological knowledge by instruments.

Time measurement is an indispensable prerequisite for astrology.

So any time piece, be it a sundial, astrolabe or mechanical clock, can serve astrological

purposes.

Occasionally explicitly astrological information, such as the tabulation of the Lords of Time,

also called chronocraters or planetary rulers, can be found on astrolabes and sundials.

Astrological information on scientific instruments and clocks has been given occasional attention.

The astronomical clock in Münster Cathedral, restored in 1540 to 1542, is equipped with

mechanically operated tablets for the indication of the chronocraters, while the clock in Rostock

Cathedral has a gravity-operated dial.

But these mechanisms indicate hours of equal length, which is in contradiction to the definition

of astrological planetary hours, that is, division of the diurnal and nocturnal arc

of the Sun into 12 hours each, which are consequently of unequal length.

The first hour after sunrise on Saturday is assigned to Saturn, followed by the other

six planets according to their orbital period and so on.

We will look at examples on some smaller instruments, which provide important data and interpretive

tools for horoscopic work, and for which the term tabular instrument may be coined, with

special reference to a unique device, owned by Heinrich Ranzow, an ardent believer in

astrology.

Tobias Volkmar the Elder, who lived from circa 1550 to 1622, the goldsmith and instrument

maker from Bunswick, had a particular liking for the display of the chronocraters, which

figure prominently on his estolaves.

Although there are a number of relevant publications, Tobias Volkmar's life and work has not yet

been fully researched.

Volkmar was a versatile and skilled goldsmith, instrument maker, mathematician and surveyor,

who had been trained from 1565 onwards in the workshop of Hieronymus Remedes, the goldsmith

in Bunswick.

He received citizenship in Salzburg in 1586 and worked as court goldsmith for three archbishops,

Johann Jakob Kühn von Belasi, Georg von Kühnburg and Wolf Dietrich von Reitenau, until 1593.

Volkmar was Protestant, and during the counter-reformation his position apparently became difficult.

He tried in vain to secure a position in Dresden, but was successful in finding an appointment

in Munich as court goldsmith and mathematician in 1594.

He not only made instruments there, but was also active as a cartographer and surveyor.

He took part in the restoration of the fortress of Umbelstadt in 1609 and with his son of

the same name, who died in 1658.

He designed the layout of the Hofgarten in Munich as well as surveying the area.

Together they also surveyed the route for a saltwater pipeline from Reichenhall to Traunstein

in 1616.

Three surviving astrolabes by Volkmar display a huge range of astrological data on the back.

Two were made in Salzburg, one dated 1594, here the back, the other 1593, and the third

was made in Munich and is dated 1601.

In addition to astronomical and mathematical problems connected with astrology, for example

house division, specific instruments could serve to display in a clear arrangement the

entangled diverse astrological patterns needed for interpretation, including the meanings

of the houses, properties of a planet, its position in the houses and signs of the zodiac,

the properties of the zodiac signs themselves, zodiacal dignities, elemental qualities, among

many others.

Usually such instruments provide important data and interpretive tools for horoscopic

work and for these devices the term tabular instrument may be coined.

Precursors of such tabulations can be found in astronomical tables of the late Middle