Jean Errard wrote a book full of examples how to calculate on the dimensions of a fortification.[br]This worksheet shows an example of his calculations..[br]The source of his book is available online at [url=https://gallica.bnf.fr/ark:/12148/bpt6k1512241w]Gallica.bnf[/url].[br]My source list: [url=http://www.fransvanschooten.nl/Stevin.htm#literatuur]Sterctenbovwing Simon Stevin (www,fransvanschooten.nl)[/url][br]