I am looking for any data on the weight of objects as they decend into the earth. I cant seem to find any, which i find surprising, that would be an ideal way to prove gravity being exclusively due to the attraction of mass. I think i am correct in saying that as you decend the weight should decrease uniformly, as there is more mass above you pulling you back, and less below you pulling you towards the core. And when you get to the centre you would be completely weightless, as gravity cancels out in every direction. That is what Newtons Shell theorem suggests; http://en.wikipedia.org/wiki/Shell_theorem is there any data on weights at different depths inside the earth? surely there must be some, i cant seem to find any.