GEBR. WICHMANN, Berlin / Germany                         (1930)
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SCALES  of  the  W I C H M A N N    »PRECISION«     Model  1417
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Front Side       [ inverse / RED ]                    Back Side
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( 0 ...  28 cm Ruler )

L1         lg( W1 = sqrt(X) )
L2         lg( W2 = sqrt(10X) )
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D          X
W1         sqrt(X)
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W1'        sqrt(X)            SIN  6° .. 18°  ===read===>>  W1'
[1/W2']    [1/sqrt(10X)]      SIN 19° .. 80°  ===read===>>  W2'
[1/W1']    [1/sqrt(X)]        TAN  6° .. 17°  ===read===>>  W1'
W2'        sqrt(10X)          TAN 18° .. 45°  ===read===>>  W2'
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W2         sqrt(10X)
SIN        2° .. 5°    ===read===>>  W2
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K1        (  W1 = sqrt(X) )3
K2        (  W2 = sqrt(10X) )3

R E M A R K S :                      (  1° = 60' ;   1' = 60" )
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The TRIGONOMETRIC SCALES are divided in MINUTES(') & SECONDS(")

Because the scales W1/W1' start at 1 and end at sqrt(10)
    and the scales W2/W2' start at sqrt(10) and end at 10
the 25 cm WICHMANN has the PRECISION of a 50 cm slide rule !!!

This historic wooden model comes in a black cardboard case.
It has a table with physical constants on its back side.
In the body under the slider is a 33 ... 55 cm ruler.

Historical Remarks ...

Its shape with screwed scales, its table with physical data on
its back side and also its cardboard case is very like the old
NESTLER - AND! the pressed initials »A.N.« on the side of the
»WICHMANN-1417«  support it: It was made by ALFRED NESTLER.

Compare the SCALE DESIGN with
    the NESTLER »PRAEZISION«,
    the POST-1442 » Dual 10"/5" POCKET-SR «,
    the FABER-CASTELL »COLUMBUS/A.Rohrberg« and
    the "modern" FABER-CASTELL »NOVO-DUPLEX«

impressum:
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© C.HAMANN     http://public.BHT-Berlin.de/hamann      03/31/08