Tuesday, November 18, 2014

Roman Dodecahedra

Roman Dodecahedra .

Andre Willers
18 Nov 2014
Synopsis :
An ancient safety lamp and heater . Only expensive metal ones partially survived . Known as Roman dodecahedrons .

Discussion :
1.Any shack dweller or army tent brat would instantly recognize them .
Fire is a deadly danger in places like army camps .
So , those who could afford it had lamps and heaters mounted in gimbals inside safety holders .
See Appendix B .

The gimbal tech was known from 200 BCE onwards .
2.Worked metal was impossibly expensive , but hardwood was easy to carve .
So the actual mountings of the gimbal would have been wood . This would have perished or any remains misclassified .
Fancy ones would have stability mountings made of metal . Officer stuff .
2.1 Like this one : the large holes indicated use as a lamp . Smaller holes would indicate heaters .
Note most of the remnants were found in colder latitudes .

2.2 A fancy officer’s heater . Will keep gloved hands nice and toasty at -10 degrees . Note that it is not a dodecahedron . A doting father’s status gift .

3.Fuel supply .
We would use some machine with a tank . A Roman didn’t think like that .
He thought “slave” .  So some shivering slave had to stand by all night to put in oil into the lamp or heater .
4. The knobs weren’t only for stability . They also enabled sharing heat while wearing mittens . The knobs functioned as holders (exactly the same as in your kitchen pots)
At least 3-4 troopies could safely warm their hands on those bitterly cold nights .

5.The stability and gimbal mounting meant that it could be wrapped in a skin or blanket as a bed-warmer .
Especially important for arthritic , elderly commanders on the Rhine . Something the Sagas never address .

6.Why did so few survive ?
Because most of them were made entirely of wood .
 Some ceramics  , too . But wood perishes , ceramic gets broken into shards and dispersed once the wood bracements are gone .
And misclassification . There are probably hundreds of remains in the basements of the big Museums .
Only fancy , rich , status items survived in some sort of shape .

7.Why no technological copying by the Goths ?
They had the metalworking and woodworking skills .
The problem was fuel . No olive oil or many slaves to feed the contraption .
Remember , the fuel container inside the gimbal had to be small and energy intensive .
They only had charcoal , so braziers were substituted .

“Warm face, warm hands, warm feet. Oh, wouldn't it be loverly?”  My Fair Lady
Toastily yours

Andre .

Appendix A

Roman Dodecahedra
Dozens of hollow, bronze dodecahedra survive from Roman times, the second to fourth century. They have been found in Great Britain, Belgium, Germany, France, Luxembourg, Netherlands, Austria, switzerland, and Hungary. Ranging from 4 to 11 cm, they are embellished with spheroids at each vertex and circular holes of various diameters in each face.  The articles by Artmann, Emmer, and Malkevitch (listed in the references) describe them further.  The 10 cm example illustrated at right is scanned from the article by Malkevitch.   Often there are concentric circles scored around the openings, as in the 8 cm example below, from the article by Emmer.
he function of these dodecahedra has not been determined.  (So it is not clear that I should list them here under the category art.)  Speculation includes: candle stands, flower stands, staff or scepter decorations, surveying instruments, leveling instrument, finger ring-size gauges, dice, a toy to throw and catch on a stick, and geometric sculpture. No one knows.
Artmann also reports one Roman icosahedron, illustrated at left.  It is also hollow, bronze, and about 8 cm in diameter.  This only deepens the mystery as to the function of these objects.
Interestingly, it was put away in a museum's basement storage, misclassified as a "dodecahedron" for forty years before someone noticed it was not a dodecahedron.  That illustrates nicely how people see things differently depending on their background knowledge.
If you read German, read this nice survey article by Bernhard A. Greiner.

Appendix B
The Gimbal
In a conversation with a friend, he pointed out that the Gimbal would be the best practical/automated embodiment to achieve arbitary Euler angle rotation (theta, phi, Xi) of an object around its center of mass.  I told him quite simply, you are good, but a guy like Archimedes would no doubt have conceived of such a leap of generalization.  Of course we first did quick check first at Wikipedia about the inventor of the Gimbal. 
To no surprise to us, the Gimbal was first described by the Greek inventor Philo of Byzantium (280-220BC).  He died only 8 years after Archimedes.
Philo described an 8 sided ink pot with holes, which can be turned so that while any face is on top, a pen can be dipped in ink, yet the ink never runs out through the holes on the other sides.  This was done by the suspension of the ink well in the center, which was mounted on a series of concentric rings which remained stationary no matter where the pot is turned.

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