Registered Forum User
Mille
Posts: 325
Join Date: Jul 2003
Location: Switzerland
Mood: Abbia Divertimento---o0o---Cassaforte Di Soggiomo
Philthy
Easy - they measure the mass of the large rock - then weigh a tiny piece of the same type of rock and measure the mass of that little bit - then they simply multiple the weight by the difference in the mass of the two pieces.