i finally found the website i've been looking for for a while.
this is the link, unfortunately the "Table of Contents" link is broken, but you can navigate by clicking the "Next Page" link.
i think this website is a wealth of information.
here is the link:
Edit by gig:
Current (29.12.2011) link: http://web.archive.org/web/200910230...2/spacing.html
Another useful link on roman legions:
Roman Legions (Thanks to Moon for providing this link)