3, 5,
7, 9) contain the letter D, and the even fingers (Nos. 2, 4, 6, 8, 10)
contain the letter N. The D indicates that the values of these fingers
relate to the denominator, the N that they relate to the numerator.
The summation of the numerical values of the whorl type patterns, if
any, appearing in fingers 1, 3, 5, 7, 9, plus one, is the denominator
of the primary. The summation of the values of the whorls, if any, in
fingers 2, 4, 6, 8, 10, plus one, is the numerator of the primary.
Where no whorl appears in a set of impressions, the primary,
therefore, would be 1 over 1. The 1 that is assigned to the numerator
and the denominator when no whorls appear is also added, for
consistency, to the value of the whorls when they do appear. It will
be understood why it was originally assigned to the no-whorl group
when it is considered how easily a zero might be confused with an O,
which is the symbol used for an outer whorl tracing.

To obtain the primary for the prints in figure 347, the number of
whorls appearing in the odd fingers is ascertained to be 2. Their
positions are noted (1 in No. 1 and 1 in No. 7) and the values
assigned to whorls appearing in those fingers are added together (16
plus 2 = 18). To this sum the arbitrary 1 is added, giving us the
total of 19, which constitutes the denominator for this set of prints.
To get the numerator, it is ascertained that there are 3 whorls
appearing in the even fingers (2, 4 and 6), the values of which are
added together (16 plus 8 plus 4 = 28). To this sum the 1 is added,
giving a numerator of 29, and a complete primary of 29 over 19.

By the word "whorl" is meant all types of whorls, including plain
whorls, central pocket loops, double loops and accidentals. The
tracing of the whorl does not enter into the determination of the
primary.

The method of obtaining the primary can probably be shown best by
illustrations. For example, assume that there is a whorl in the right
index finger only. The value of a whorl in this finger is 16. When 1
over 1 is added the resulting primary is 17 over 1. If a whorl appears
in the right thumb and right index finger, the value is 16 over 16
plus 1 over 1 giving a primary of 17 over 17. If whorls appear in both
index fingers, the value is 16 over 2 plus 1 over 1 giving a primary
of 17 over 3. When whorls appear in both thumbs and both index
fingers, the primary is 21 over 19 and is obtained by the addition 16
plus 4 plus 1 over 16 plus