Foot (unit)

A foot (English foot, plural feet) or shoe is a Previously-used in many parts of the world length dimension which is usually 28 to 32 cm measured depending on the country, in extreme cases, 25 and 34 cm. It is adjacent to the finger width, hand width, hand span, the cubit, the step and the cords of one of the oldest units of length. These units were probably used before the invention of writing.

The only one still Fußmaß usual, the English foot is 1 ft = 30.48 cm ( 12 inches), which is almost the size corresponds to 48 ½. Although it is not an SI unit, the unit foot is also used internationally still common, especially in the maritime and aviation.

Origins

Since when the foot is used as the unit of measurement is controversial. Definite conclusions can be drawn from the earliest finds of standards. The oldest undamaged found object of this type is the so-called Nippur cubit from Mesopotamia. Notches to open up to 30 subunits finger's breadth ( 1.73 cm digiti à ), from which the units of measurement arise feet with 16 digiti ( 27.6 cm ) and the hand width ( palmus = 4 digiti ). Try to check the length of the ulna on buildings, resulting in an average of 518.65 mm.

Whether it - as in the case of the Megalithic Yard - a common Urmass can be derived, is controversial in the scientific world. Identical lengths or their subunits in different cultures could also be a consequence of the unity of body dimensions on which they return.

Antiquity

Even before the Fourth Dynasty pharaohs Egyptian surveyors divided the Nippur cubit only in 28 parts, to correspond to the trigonometric approximation ( 20 × √ 2 ÷ 28 ≥ 1). Thus, the foot grew as a measure to 51.8 cm ÷ 28 × 16 ≈ 29.6 cm. Exactly this length also had the Roman Fußmaß. Accordingly, the megalithic or Nippur foot and the Roman feet maintain a ratio of exactly 28 to 30

A foot (Latin pes ≈ 29.6 cm ) is thus four handbreadth (Latin palmus ≈ 7.4 cm ) or sixteen fingers wide (Latin digitus ≈ 1.85 cm ). Besides the official pes monetalis the Roman north-western provinces and the so-called pes Drusianus ( ≈ 33.27 cm) was used, which was digiti longer compared to the official Fußmaß by about 2 in some parts. He was named after Nero Claudius Drusus commander. The " four-foot level " were called in late antiquity Latin ulna (ulna ). The " measure of 1 ½ feet " is the natural cubit (from the Latin cubitus ). The " five-foot level " is the double step (Latin passus ). The English yard has exactly three feet.

In ancient Greece, for example, there was next to the mostly used, actual foot (Greek pous ) to 16 digits and a so-called Pygme to 18 finger widths. This Pygme ( underarm to wrist) was often referred to in translations in the absence of a suitable word as " foot". Nevertheless, it can be stated that over the entire history of civilization across the foot is always 16 digits, with the "fingers" as the true base unit can be viewed.

Among the manifold, always derived from one another Greek systems above all the common Greek foot to call are ( scientifically since Heron as Pous metrios called ), which later became the Austrian foot was, and the relevant particularly for the geodesy of Eratosthenes Greek Cyrenaic foot of the ancient world.

Middle Ages and Early Modern Times

Until the Middle Ages, with its preference for the duodecimal of the foot was divided into sixteen instead of twelve subunits. This gave the thumb's width, called the Customs (Latin uncia, Eng. Inch, French pouce ). In other cultures, such as in Japan or China, length measurements are known in the size of the human foot.

A Carolingian foot measured 32.24 cm, the " Paris Königsfuß " 32.48 cm (presumably derived from pes Drusianus ) and the widespread Rheinfuß just 31.4 centimeters.

A statement to the boundary survey between the County of Nassau and Hesse- Darmstadt from 1719 sets in section 5 that should be used to measure " a rod to 18 shoe, the shoe to 12 inches ."

In almost all structures of the Middle Ages, the foot was used as Grundbaumaß. It can be reconstructed from the width dimensions of the respective buildings. The various Dombauhütten each used their own feet that were either antique foot measurements or their derivatives.

As they tried in the early modern period, " a fair Meßrut " to create as averaging, shows the following text of the mathematician, surveyor and town clerk Jacob Köbel from Oppenheim from 1535:

" A measuring reed by the right kind of artificial VND Common use are thus made ​​sol. It should sechtzehen man / small VND big / how the vngefehrlich go to another Auss of Churches / each represent a Schuch before the others so / and a Lenge / sechtzehen the same as straight Schuch begreiffet / measure / sameness Lenge is / and sol Being / a meet / common measuring rod / so you should measure the Feldt / ... "

With the introduction of the decimal meter in France in 1793 was broken for the first time in human history, with the use of any specific human-related basic dimensions as well as with the traditional reference to other, already existing degree. The new reference should now be the circumference of the earth. In certain areas, such as land surveying and navigation, but previously distinct geographical miles were (eg 1 degree equator long) used and derived quantities. The meter was defined as purely abstract ten -millionth of the distance from the pole to the equator. As a result, the classical human Fußmaß disappeared within the scope of the meter.

In order to simplify and better acceptance of the conversion to meters was there in the 19th century and there trying to bring the old Fußmaß to round values ​​of the new system. So there was the Grand Duchy of Hesse a foot of 25 cm, in the Duchy of Nassau as high as 50 cm (shoe size 75! ), And the Grand Duchy of Baden and Switzerland was a walk of just 30 cm. In this case, the root was mostly divided by ten. Other authorities confined themselves to define their feet and other units depending on the metric system.

German-speaking

The various old German footages have been abandoned by the North German Confederation and the adoption of its laws in the founding of the German Empire (1871 ) and the subsequent German accession to the international Metre Convention (1875 ) entirely. In Austria most was the pous metrios to 31.61 cm.

Regional corresponded to the foot of the shoe.

Examples of the foot measurements in some German cities and countries:

• 281.98 mm in Weimar
• 283.19 mm in Saxony
• 284.61 mm in Frankfurt am Main
• 286.49 mm in Württemberg
• 286.5715 mm in Hamburg
• 287 mm in Hesse- Kassel
• 288.14 mm in Hesse- Darmstadt
• 289.35 mm in Bremen
• 290.50 mm in Aschaffenburg
• 291.86 mm in Bavaria
• 292,10 mm in Hanover
• 296.17 mm in Augsburg ( Roman foot )
• 296.41 mm in Oldenburg ( Roman foot )
• 303.75 mm in Nuremberg
• 303.95 mm in Meiningen -Hildburghausen
• 313.85 mm in Prussia ( Rheinfuß )
• 316.102 mm in Vienna, Austria ( Pous metrios )

Reformed foot measurements in the Confederation of the Rhine ( 1806 ) and after the Congress of Vienna (1814 /15):

• 25 cm in Hesse
• 30 cm in Baden
• 33 ⅓ cm in the Palatinate

European footages

Source:

Presence

The international unit symbol is now ft for engl. foot or feet, often abbreviated with the sign for a minute of arc ' ( in Unicode, the " PRIME " character U 2032 ), substitute half the smart quotes '. What is meant is always the international foot ( " Anglo-Saxon Kompromissfuß ", 1959), representing one third yard or twelve international customs per 2.54 cm, thus precisely measuring 30.48 cm:

U.S. land surveying

In U.S. land surveying next to it holds the former definition, fit in exactly 39.37 inches in one meter ( instead of 39 47/127 = about 39.370 078 740 ). This is the international foot exactly 0.999 998 times as large as the U.S. survey foot, that is 0.0002 % or a five hundred-thousandths smaller.

Science

In science, international applies the decimal metric system, and even in the U.S., the foot is no longer used in this area.

The old units, however, lead to this day to conversion errors. So the construction of the Hubble Space Telescope, the air density was reduced in the wrong lab on the vacuum and required subsequent repair by astronauts.

Technology

In many technical areas, there are still walking and particular customs, in order to be compatible with the important North American market. As in most countries, the use of the metric system is required by law, these units (eg, 17 "monitor ) appear only in generic terms to, or the actual foot and inch dimensions are converted to metric and then often rounded. For threads or screws these small differences sometimes lead to problems.

Logistics

Many details are given in feet and inches, such as ISO containers (20 feet and 40 feet).

Aviation

Direct values ​​in feet are most commonly encountered in aviation, where they pose as the most common unit of feet altitude. In geographical elevation data in aeronautical charts (especially for airfields and mountains ) is used in connection with the statement in the foot of the term " elevation " ( ELEV ). In controlled airspace, the flight levels (English: flight level, FL) are named for their height in multiples of 100 feet. Example: The altitude " FL120 " means: " 12000 ft above the reference plane ."

Shipping

Many dimensions are based on feet and inches or still directly specified therein. Dimensions in building codes for eg hatches, ceiling heights or the guard rail were defined in feet or inches and are now given as millimeters ( height of the railing 2 feet corresponds to 610 mm, distance between the supports at most 7 foot corresponds to 2134 mm). Limits for ship classes are often entire footages. A register ton is 100 cubic feet. In the manufacture of chain links of the customs is mostly used, while the products are excellent in millimeters ( the links of a ¼ - inch chain are 6.35 mm thick, but are referred to as 6- mm chain; ⅜ inches are 9.53 mm, but 10 mm are sold, and ½ inches are 12.7 mm, but mean 13 mm). On all official U.S. nautical charts and nautical publications water depths are given in feet. By contrast, the British Admiralty charts are now almost continuous metric.

Even if it's not true exactly, use non Englishman feet values ​​in the name of a boat type or brand, to specify the boot in more detail (boats Class Melges 24 are 750 cm long, the Swan 48 has 1483 cm and not correct 1463 cm).

Sports

In some sports dimensions are original round feet values ​​, but are now often specified in meters, yet only sometimes rounded to smooth values ​​. The basketball hoop, for example, depends 10 ft high (converted 3,048 m), the football goal is 2.44 m high and 7.32 m wide ( originally 8 ft × 24 ft).

Organ Building

In organ building, the foot is now used to indicate the pitch of organ pipes. The so-called Fußtonzahl indicates the sounding pitch of an organ register. In an 8 'stops the C key can also sound the note C, with a 4' stop the sound c0, etc. This is based on a theoretical standard pipe for the C key. For today's mood in organ building has one foot about 32 cm. However, depending on the type differs, the actual length of a pipe with the same pitch from the one given in foot length.

The differences of the regional standard foot measurements in the historic organ building played at the mention of Fußtonzahl not matter because it was only given coarse. For example, the measure was 2 ⅔ written ' regularly as 3'.