-- -- -- --
7 1 10 0

To obtain the figures of the fourth column this difference must be
doubled, thus

7 1 10 0
2 0 8 0
-- -- -- --
9 2 0 0

To obtain the black numbers of the next (third) column, the lower cipher
symbol of which is wanting, we add the former difference:

9 2 0 0
1 0 4 0
-- -- -- --
10 2 4 0

This decrease in the difference is unusual and indicates some error. This
idea seems to be confirmed in the following way: In order to obtain the
numbers of the next (second) column it is necessary to add three times
the former difference, thus:

10 2 4 0
3 0 12 0
-- -- -- --
13 2 16 0 Second column, Plate 71.

If the increased difference, 2, 0, 8, 0, were retained after its
appearance the result would be as follows:

7 1 10 0 Fifth column, Plate 71.
2 0 8 0
-- -- -- --
9 2 0 0 Fourth column, Plate 71.
2 0 8 0
-- -- -- --
11 2 8 0 Third column, Plate 71.
2 0 8 0
-- -- -- --
13 2 16 0 Second column, Plate 71.
2 0 8 0
-- -- -- --
15 3 6 0 First column, Plate 71.

Adding the difference, 2, 0, 8, 0, to the third column, Plate 71, thus:

10 2 4 0
2 0 8 0
-- -- -- --
12 2 12 0

we obtain the red numerals inserted in the third column. It is probable
that the original or some subsequent scribe, observing an error at this
point, inserted these figures as a correction. If so, he failed to remedy
the confusion apparent in this portion of the series. The sum of the
entire series is 303 years (360 days each) and six months, equal to 420
cycles of 260 days.

I am strongly inclined to believe that this section and also pages 24 and
59 are interpolations by some aboriginal artist of a mathematical turn
and advanced ability in this direction, who has given these high series
more as curiosities than with reference to any specific dates or periods
of time.

[Illustration: FIG. 371. Specimens of ornamental loops from page 72,
Dresden Codex.]

Commencing in the sixth column of Plate 71_a_ and running through 72_a_
to the second column of 73_a_, is a numeral series which presents some
peculiarities that baffle all attempts at explanation. Contrary to the
rule which prevails in these pages it ascends from left to right and has
no day symbols connected with it. In ad