Excursus from the main page's chapter :  " The digital foot already exists ".

The Viennese yard is exactly  1728  /  1000  Nippur cubit.

The third part of this Viennese yard equals the length of the modern digital foot.

The deduction of the Viennese yard by ancient measures (number of digits) :       3 0 6 0 9 0     1 8 3 6 5 4 7 2 9 0 10 8     1 6 3 2 4 8 6 4 8 0 9 6	Three raw Nippur cubits :   3 × 518.40 mm 90 × 17.2800 mm = 1555.24 mm   Six Nippur pygmes :   6 × 311.04 mm 108 × 17.2800 mm = 1866.24 mm   Six attic-olympic feet :   6 × 311.04 mm 96 × 19.4400 mm = 1866.24 mm 96 attic-olympic digits  are  100 Viennese digits  96 × 19.4400 mm = 1866.24 mm   100 × 18.6624 mm = 1866.24 mm
Six Viennese feet equal two Viennese yard,*  i.e. the Viennese klafter.	Thus these idealistic Viennese measures : Foot : 16 × 18.6624 mm = 298.5984 mm Yard : 48 × 18.6624 mm = 895.7952 mm Klafter : 96 × 18.6624 mm = 1791.5904 mm

* The Viennese yard is the Stephansdom linen-ell, Leinenelle. The Viennese ell or drapery-ell, Tuchelle, is deduced by that yard. (See below.)

In a early fit of decimalisation the attested attic-olympic orguia  – a klafter measuring 96 digits –  was shared into 100 parts.

From this attempt results the Viennese digit of about 18.66 mm. Naturally, the real Viennese klafter equals only 96 new digits.

Caution :  Don't confound the Viennese measuring system and the Austrian system.

The Austrian Klafter  – legal between 1756 and 1871 –  was defined, in 1760, by Joseph Liesganig as 1.02764 toise de Peru exacly one. Since 1799 the French toise is 27 000 / 13 853 metres exactly one. So, the historical Austrian Klafter is : 2 6 × 3 3 × 5 8 × 7 -1 × 23 -1 × 1117 -1 × 1979 -1  =  1.896 6139 m.   Face of these three doubtfull prime factors :   23,  like  1117 and 1979 : BI-SMH prefer the 7-smooth :  2 4 × 3 3 × 5 -7 × 7 3  =  1.896 6528 m. This gives a Klafter 38.898 µm shorter, i.e. minus 0.002 051 %. Whenever the Austrian klafter is mentionned on this domain, that defined, idealistic value is meant. It is identical to the ancient Greek pous metrios.

The Viennese Klafter equals two Viennese Stephansdom's yards. Both Viennese ells are attested since 1685, but should be mediaeval. The Viennese yard  –  see above  –  equals 1728 / 1000 Nippur cubit. The value of the Viennese Yard :  Since the raw Nippur Cubit equals  2 2 × 3 4 × 5 -4  =  0.5184 metre, the idealistic Viennese Klafter is  2 6 × 3 7 × 5 -7  =  1.7915904 m. Thus, the idealistic Viennese yard equals 895.7952 millimetres. The Austrian engineer Franz Twaroch measured  896 millimetres. This gives a yard exactly 0.2048 mm shorter, i.e. minus 0.022 857 %. So, the Stephansdom foot and the idealistic digital foot are identical. *

one Austrian foot

1 ×  2 6 × 3 2 × 5-4 × 7 3

=

316.1088 mm

≠

the Viennese foot

1 ×   2 8 × 3 6 × 5-4

=

298.5984 mm

one Austrian klafter

6 ×  2 6 × 3 2 × 5-4 × 7 3

=

1896.6528 mm

≠

one Viennese klafter

6 ×   2 8 × 3 6 × 5-4

=

1791.5904 mm

*  In ancient times, according to the statistical ressearches of  R.C.A. Rottländer, the metrological incertitude factor was generally about  ± 0.17 %. Of course, it diminished since Renaissance times. However, during the European Middle-Ages, a precission of  ± 0.02 % was certainly excellent. Therefore, a difference of 0.02 % is not significant. Thus, the Viennese yard and the length of three digital feet can be considered to be identical.

Strictly, that justified reproach could be expressed : Both values are not comparable,  because the first one is a measured  value with a millimetre - precision,  the other one is a defined value,  3 × (2 8 × 3 6 × 5 -4)  =  895. 5984 millimetres, four  right-sided decimal positions. However in reality, a measure of    896 mm must be inside the interval :  895. 5 and 896. 4999 mm. In all cases, the measured Viennese yard is inside  ± 0. 17 %.   Measured yard 896 mm   Idealistic yard 895. 5984 mm   Scientific yard 895. 7464 mm   maximum: 896.5000 mm   + 0.079 %     + 0.084 %   supposed: 896.0000 mm   + 0.023 %     + 0.028 %   minimum: 895.5000 mm   – 0.033 %     – 0.028 %

The deduction of the Viennese ell, also said : drapery ell, by the Viennese yard, also said : linen ell,

according to the works of Dipl.-Ing. Franz Twaroch, Vienne :  "Die Maßstäbe am Wiener Stephansdom" in Wiener Geschichtsblätter 57/2002.

Whilst the Viennese foot and yard was unused after Middle-Ages, the drapery ell kept its legal status in Austria till 1871, next to the Austrian foot. (See above.)

From the two measures – materialised as standards outside of the cathedral at the left of its main door – only one posseeds subdivisions. This is the drapery ell.

According to the ressearches of Franz Twaroch, its total length is 77.6 cm, subdivision marks are reported at 1/8, 1/4, 1/3, 1/2, 2/3, 3/4 and at 7/8 of ell's length.

In his publication :  "Die Maßstäbe am Wiener Stephansdom", Wiener Geschichtsblätter 57/2002, he demonstrated the connection of the two reported measures.

Therfor see this image below, click on to enlarge it. Parts of his works are avaibable in a third work as .ppt-document – on a slow server ! – at Viennese Univerity.

Here a copy of Twaroch's original draw, which is an extract of the quoted " Normen und Regelungen, St. Stephandom im Mittelalter ", Vienne 2003, I. Pastner and S. Haiden, including the lengths measured by F. Twaroch. If Franz Twaroch noted "Roman feet", it is however proofed, by different works *, that the Roman foot approached to the value 296.35 mm, not about 298.65 mm, but, Twaroch contribued a precious work for the understanding of the measures. * Other references : Vormetrische Längeneinheiten by Rolf C. A. Rottländer, Rottenburg / Köln Recovery of the Ancient System Foot/Cubit/Stadion — Length Units by Dieter Lelgemann, TU Berlin. On the Ancient Determination of Meridian Arc Length by Eratosthenes of Kyrene Dieter Lelgemann, WS – History of Surveying and Measurement, Athens, Greece, May 22-27, 2004. Knobloch, Eberhard, Dieter Lelgemann und Andreas Fuls: "Zur hellenistischen Methode der Bestimmung des Erdumfangs und zur Asienkarte des Klaudios Ptolemaios." zfv (Zeitschrift für Geodäsie, Geoinformation und Landmanagment) 128. Jahrgang, Heft 3/2003, S. 211-217.