Not sure if this applies to exactly what you are asking, as far as location. I recently contacted a historian, Monument Director of Sales, and Cemetery, to locate family members who were unmarked. All of these gentlemen are very honorable, long time residents, and up in years. Not internet handy. They looked up manually and confirmed hand written documents, and one fellow, drove out and used hand rods, or dowsing rods, and found the dimensions, by hand and located them all. I am familiar with this, and its a skill still used to find water, electric and other things in the elements. There are actually clubs, that do this, and teach others, like manual/natural metal detecting. This is how its been done for 1000's of years. Science and tradition still exists..!