Roman camp - units of measure used by Polybios

[triarius354]

Hi

I'm currently reading dr Dobson's thesis on Roman camps at Numantia, and I'm looking for metrological informations about Polybios' history.
What kind of foot (pes) does he uses? Dr Dobson writes about "hellenistic foot" (p.81) - is it the same as "royal foot" (pous basilikos)?
Why this one, and not the 0,296mm foot? If Polybios in fact was refering to "royal foot" then his description of equipemnt would be very strange (roman scutum - 4 feet high - more than 1,4m!)

Any book titles dealing with ancient metrology also welcome

Thanks for any help