Arithmetic proportions, and a note to send for wheat
Continuous and discontinuous number series, with a reminder to fetch coarse wheat from Florence.
In red chalk Leonardo sets out short number series to illustrate arithmetic proportion: the run 1 2 3 4 5 6, whose constant differences he labels 'excesses', he calls continuous arithmetic proportion, while 1 3 5 7 9 11 and the group 3 7 9 13 are marked discontinuous. Beneath the mathematics he adds a personal reminder to have ears of coarse wheat sent to him from Florence. Rows of single and paired tallies mark the constant differences between the terms.
On this page
Continuous and discontinuous arithmetic proportion
The series 1 2 3 4 5 6, separated by equal 'excesses' (differences of 1), exemplifies continuous arithmetic proportion, while the odd-number run 1 3 5 7 9 11 and the group 3 7 9 13 are noted as discontinuous. Rows of tallies (1 1 1 1 1 and 2 2 2 2 2) mark the constant differences between successive terms.
Reminder to send for wheat from Florence
Below the calculations Leonardo jots a memorandum to himself: to have ears of coarse, large-grained wheat sent from Florence. It is a practical reminder set down among the arithmetical notes.