Supplementary materials for
The First (Known) Statistical Graph:
Michael Florent van Langren and the "Secret" of Longitude
Michael Friendly, Pedro Valero-Mora and Joaquíin Ibáñez Ulargui
The 1644 graph
Other images and data
La Verdadera
Van Langren's cipher
In La Verdadara, van Langren says (p. 6)
Van Langren began the study of the Longitude for sea and land by means of the Moon in the year 1621. In 1625 he informed the infanta Isabel about this method to calculate the Longitude, as well as a second method that Langren had discovered (that it is written later in dark letters), as it is known from a letter that infanta Isabel wrote to his Majesty in the same year of 1625.
and includes the following ciphered text at the end of p. 8.
There are several open questions that arise from this:
- what is the general form or method of the cipher (substitution, transposition, anagram, etc.)?
- what methods can be used to attack it?
- if there is a cipher solution, does van Langren's second (hidden) method
differ from what we have inferred from
other sources.
For those interested in pursuing these questions further, we provide the following
resources:
Note that it was not unusual for scientists in that time to publish declarations of
discoveries in code, often using anagrams,
to be able to claim priority, while concealing their
method. See:
