#2 in Mathematics bestsellers
#2 in Mathematics top-rank
"Showing how a man may with privacy and speed communicate his thoughts to a friend at any distance."
This is one of the first published works on cryptography, secret inks, signalling and secret codes - methods later used in thought reading acts. It is therefore not only of interest to cryptographers and historians of cryptography, but also to people who study silent codes and other related methods in mentalism.
[Please note that this is not a simple scan of an old book. This old book has been typed in and digitized with the utmost care, using an appropriate font with the correct glyphs to make this look exactly as the original. Literally hundreds of hours have been spent to restore and digitize this wonderful work. This sets a new standard for the preservation of very old books.]
1st edition 1641; 2nd edition 1694; PDF based on 2nd edition, 192 pages.
word count: 31789 which is equivalent to 127 standard pages of text