Arbeitskreis Geschichte des Kartonmodellbaus (AGK) e.V.

AGK members discovered earliest known card model print

The earlist known card model print was discovered by members of the "Arbeitskreises Geschichte des Kartonmodellbaus" (AGK) when they visited the Germanisches Nationalmuseum (Germanic national museum) in Nuremberg as part of the programme of their 2004 annual meeting. It is a woodcut print on cardboard; the built model is a sundial in the form of a crucifix. A Latin inscription on the base names the Nuremberg mathematician Georg Hartmann and dates the print to the "Anno obsidionis", the "year of the siege".

The drawing style points to the first third of the 16th century, which makes this print older by some years than the images and model prints by Hans Döring that accompanied the book "Kriegsbeschreibung" by Reinhard Count of Solms of 1544/45; so far these prints were thought to be the oldest existing examples of card models.

The designer
The theologian, mathematician and precision engineer Georg Hartmann of Nürnberg was born on 9 Februar 1489 in Eggolsheim near Forchheim (Franconia); he died on 9 April 1564 in Nuremberg. Hartmann studied theology and mathematics in Cologne from 1506 until about 1510 together with Heinrich Glareanus (1488-1563). After an educational journey through Italy he became vicar of the St. Sebaldus church of Nuremberg in 1518; that means he had decided to settle in one of the most important metropoles of Europe as far as trade and science were concerned. Here he had access to both the valuable materials he needed to build his instruments and to the interested customers who had the money to buy them. In the renaissance epoch, Nuremberg and Augsburg belonged to the few cities that were famous for their manufacture of scientific instruments, among them travel sundials (called Kumpast or Combast). In the inspríring climate of a free imperial city Hartmann became an expert builder of measuring instruments. Beside various sundials he created astrolabes, sun quadrants and astronomical and astrological reference discs; probably he also made earth and celestial globes, armillarspheres and wall sundials. Popular material were pear and box tree wood but also brass and ivory. Georg Hartmann had far-reaching contacts and a lively correspondence with many scientists and rulers of the time.

Bogen The model
Georg Hartmann printed the model sheet from a woodcut plate onto handmade paper that consisted of 2 layers, glued together. The sheet size is 44.5 x 17.5 cm. He selected a model construction in which all model planes are connected with each other, i. e. the complete model consists of just 1 cut-out part. The way he designed his model deserves admiration; even if the end result seems obvious we must assume that it took many attempts to bring it into the form we see. The way the planes of the foot and the arms of the cross touch each other exactly as required to glue them, and the way he designed the glue tabs, shows his mastery of geometrical design. The way he arranged the parts makes for an easy assembly of the model; no instructions are necessary, the parts fold into each other naturally and easily. Where parts touch that must be cut apart he marked it by applying short vertical lines to the contours. He did not mark ridge and valley folds with distinct line types as it is usual today, but in fact this does not seem necessary on a model like this and if the fold lines are scored sufficiently. And there are just 2 glue tabs that actually need a valley fold: the ones to the right and left of the evangelist Mark; all other folds are ridge folds. The drawing and the design are very precise, you can assemble the cross exactly and without problems. We conclude that Hartmann must have been an expereinced model maker and designer. The clean and straigt lines of the print prove his skills as a craftsman. A nice touch is the fold-out protractor that you can set to any angle required for a specific location.

Imagery and dating of the sundial crucifix
Georg Hartmann chose the symbolic old-testament "bronze serpent" Nehushtan and the new-testament crucification of Christ as motifs for the graphic design. The 4th book of Moses 21, 4-9 tells about the Israelites, that were attacked by desert serpents on their search for the promised land. By erecting a bronze serpent and worshipping it the Jews who received venomous bites were saved. There is a direct reference to John 3, 14-15 "Just as Moses lifted up the snake in the wilderness, so the Son of Man must be lifted up, that everyone who believes may have eternal life in him."

Hartmann references an actual historical event in the Latin text at the bottom surface of the cross. He does not give a year as usual but uses the formula "Anno obsidionis" which is a bit of a conundrum to us (though other prints actually give a month and day). The full inscription is:
Nos autem gloriari oportet in
cruce domini nostri Iesu Christi, in quo
est salus, vita et resurrectio
nostra, per quem salvati et liberati
Georgius Hartmann faciebat Noremberge Anno obsidionis.


This translates to: "It is for us to praise the cross of our Lord Jesus Christ which carries our salvation, life and resurrection. By whom we have been redeemed and liberated. Georg Hartmann of Nuremberg made it, in the year of the siege." There are two clues to the exact dating of the model: For one, the stylistic classifiaction as belonging to the first third of the 16th century (the time of Dürer), and Hartmann's indication about the "year of the siege". It so happens that Suleiman the Magnificent besieged Vienna in 1529 until he was pushed back towards Hungary by the troops of King Ferdinand I. (1503-1564). We know that Hartmann had contact with both Vienna and the Ottoman empire. More than once he made sundial faces with various pole heights for export in other regions; he profited from the trade connections of Nuremberg that reached far outside of Europe. He also produced prints for the Turkish market; we know of a woodcut print for a folding or "diptychon" sundial that is preserved in the Bayerischen Staatsbibliothek (Bavarian state library). The Arabic inscript names the 42th parallel, that of Constantinople which was Suleiman's capital from 1520 to 1566. It is remarkable that this print also carries the same formula "faciebat Anno obsidionis". Therefore it seems certain that the "year of the siege" refers in fact to the siege of Vienna in 1529. Hartmann was a friend of the mathematician and architect Johannes Tscherte who lived and worked in Vienna and who planned Vienna's new ring walls, by order of Ferdinand I., after the siege. And King Ferdinand I. was known to Hartmann personnally; three times he came to Nuremberg to have demonstrated Hartmann's instruments to him.

Using the cruciform sundial
A sundial is an instrument to measure time by measuring the march of a shadow (thrown by a gnomon, i. e. a pole, edge or point) across a dial. To give the precise time, since the 15 century the gnomon was oriented parallel to the axis of the earth, pointing towards the North Star; its angle phi is linked to the parallel of its location. Only then the sun seems to revolve around the gnomon. Gnomon and dial usually did not just indicate the time but also linked it to calendar, astronomical, astrological and geographical information. For this special sundial Georg Hartmann chose the form of a crucifix. Cruciform sundial were not unusual at the time and often decorated with a figure or image of a crucified Christ. Cruciform sundials must be placed on a horizontal surface and then oriented in north-south direction with the aid of a compass. The cross must then be pivoted until its arms point towards the North Star, i. e. they are then parallel to the axis of the earth. In Nuremberg, for example, the pivot angle would be 90-49 = 41°.The edges of the top of the cross now throw a shadow that indicates the "true local time"; all sundials at the same longitude will show exactly the same time (if they are set up correctly). At the time, their precision was sufficient; it was only at the end of the 18th century that it was found, with the aid of precise pendulum clocks, that sundials will "run fast" or "run slow" up to 16 minutes in the course of the year – a deviation caused by irregularities in the rotation of the earth. The error can be corrected with the aid of tables that show a correction value for each day of the year. Besides the inscription, the bottom of the Hartmann sundial has a protractor to help in adjusting the sundial to the correct angle. After cutting it out you can fold in according with the parallel of a certain location (49° for Nuremberg) and hold it with index finger and thumb to find the correct angle. A small pointer on the sundial gives the compass deviation at that time, 10°, to help in orienting the sundial with a magnetic compass.


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