Not without an x-ray machine.
Take something like a 1/4" carbide drill, start drilling, then mark it when it pops through.
Another thing you can do is take something like a spud bar and thump the concrete, You will be able to tell where it is hollow under the concrete and where it is solid by the sound. Where you hear that it is hollow underneath, drill the concrete in that area. That will give you a good idea as to the thickness.
If the concrete is in good shape, and it's a hundred years old, it may be pretty damn tough. In my hometown, they have the first concrete street in America. A few miles west of there, a railroad overpass was built. The concrete was so tough that they worked with a wrecking ball, jackhammers, and could not get it broke up. This was two walls on each side of the road. They finally had to dig back behind it, take some pumper trucks and wash out the dirt to undermine it and it is now buried.
So with that little tidbit of info, what are your plans on doing with the old concrete? And better yet....any pics of what you are working on? If so, post 'em up!!!
