Thursday, August 22, 2013

Introduction to a Metrology Course for an African Air Force Ally

  The following is an introduction to a Metrology / Calibration (PMEL) course I developed for an American ally in Africa.   These military officers had spent their lives believing that Western Nations have the only technically competent societies capable of precision and accuracy.  This introduction was to reacquaint them with the idea that their ancestors were doing precision work and had precision standards when the western nations were painting themselves blue and running naked into battle.   This course was presented by my female offspring, which was an extreme cultural experience for these officers, but at least with this introduction, all the inferiority complexes went out the window. 

The outline of chapter 1:

1.                  Introduction

1.1              History of Measurement and Calibration

The history of measurement begins with the discrimination of the ages of Egyptian weights and capacity measures.  Increased knowledge of prehistoric weights and measures supercedes most of the fragmented and vague statements of ancient authors.

Lineal measures:  The earliest known is the standard cubit used in Egypt from the time of the predynastic royal toumbs onwards.  The first accurate example is in the size of the pyramid of Snefru (3rd dynasty) at 20.62 modern inches.  The cubit was defined more exactly in the pyramid of Khufu.  The pure system was:

                        Meh       = 0.206 inche
                        100 meh = 1 cubit = 20.62 inches
                        100 cubits = 1 khet = 2062

The cubit was mixed with other systems:

                        Zebo  (digit)  =0.737 inches
                        4 zeb0 = shep = 2.974 inches
                        7 shep = cubit = 20.62 inches
                        100 cubuts = khet = reel = 2062 inches
                        120 reels = 1 ater or skhoinos

Capacity measures:  The approximate values of Egyptian capacities are anciently stated by the odd quantities that certain vases held.  The first measure was the Egyptian hen which was about 29.1 cubic inches.  The values of these old capacity measures are:

                        Ro = 3.64 cu in
                        8 ri = hen = 29.1 cu in
                        4 hen = hennu = 116.4 cu in
                        10 hennu = apt = 116.4 cu in
                        4 apt = tama = 4656 cu in
                        25 tama = sa = 116.400 cu in

The precision of the capacity measure has been measured by comparing  five regular unmarked  measures of metal and stone is 29.2 +/- 5 cu in, ten bronze vessels  is 29.0 +/- 0.3 cu in, and 8 marked vases is 29.2 +/- 0.6 cu in

Weight Measurements:  The Egyptian weights are by far the best known and most published.    Each people or tribe tended to have had a separate weight standard and these were brought to different countries by invasion or trade.  Those standards which were most alike gradually approximated by errors of copying, and lost their individuality.  Seventeen standards in Egypt, which had originally come from foreign sources became simplified into 8..  The Peyem standard is marked on three weights of 116, 121, and 124 grains.

                        n = 30 grains
                        4n = payem = about 120 grains
                        10 payem = noshem = 1200 grains
                        10 noshem = r = 12000 grain           
                        4 noshem = s = 48,000 grains

            a grain is about  0.0648 grams

Measurements throughout the world range:

Anoman         -           Ceylon
Berri               -           Turkey
Capicha                      Iran
Duin                -           Netherland
Elle                  -           Latvia
Fanega            -           Argentina
Gallon             -           US / UK
Hiyaka-me      -           Japan
Immi               -           Switzerland
Joch                _          Austria
Keddah          -            Egypt
Li                    -           China
Mahud                        Arabia
Nia                  -           Thiland
Oke                 -           Cyprus / Egypt / Turkey / Greece
Parsec             -           Astronomy
Quart              -           US
Ri                    -           Japan
Ser                  -           India
Toise               -           France
Vara               -           Portugal
Wigtje -                      Netherlands
Yard               -           US / Mexico
Zolotnik          -           Russia

There are over 700 modern local major units of measure today.  These do not include subunits or unit multiples such as micrograms or kilometers. 

The Metric System:

 Fractions and multiples of this system, based on 10.  The weights and capacities would derive from these measurements.  This was the first metric system.  The French, after their revolution, wished also to change the old order.  Dr. Franklin’s system, became the basis of of their new system.  The length of the meter was later established as the length of a metal bar c 1875) , and still later (1927)  1,553,164.13 wavelengths of the red light emitted by a cadmium vapor lamp excited under specified conditions.  The United states adopted the metric system by treaty signatory and act of congress.  However, Wilber and Orville Wright built bicycles in inches and later airplanes in inches.  The Great airplane companies followed suit, and aircraft were built in inches.  Millions of tools were made in inches, special tools for airplanes.  The old systems are so tenacious, that In spite of the US Congress passing metric System laws in recent years, mother still cooks using cups, table spoons, tea spoons, dashes, pints, and quarts.

The expense of re-tooling mechanics and assembly lines for metric production and maintenance has resulted in a general lingering of the English system.  In recent years, the US automotive industry, because of competition form metric countries, has proceeded from inches to soft metric to hard metric.  Soft metric is using metric sized that can be handled by English tools, eg.  ½ inch wrenches can turn 11 mm nuts.  Some aircraft systems are just now becoming all metric.  Yet, even now, spacecraft have been lost because engineers did not appreciate the differences between English and metric measurements.

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