Need help with a topo symbol

[WIDirtFishing]

Was wondering if anyone could help me out with this topo symbol. Not sure what it means and was hoping some pros here could throw me a bone.
It is a map from the 30's and the same symbol appears 3 times on a large map in different spots

 

[ticm]

Was wondering if anyone could help me out with this topo symbol. Not sure what it means and was hoping some pros here could throw me a bone.
It is a map from the 30's and the same symbol appears 3 times on a large map in different spots

That black square indicates a house if that's what your asking.

 

[WIDirtFishing]

Oh sorry; I should've specified. I meant the BM X 641

 

[WIDirtFishing]

nevermind; its a Benchmark for elevation. Thanks Though

 

[TerryC]

The "BM x 641" means there is a "bench mark tablet" there. That particular tablet is 641 feet above sea level. The best representation of a bm tablet I have ever seen is the one in the "Long Term Visitor Area" south of I 10 near Quartzsite, AZ, on US 95 If you go south into the camping area and watch to the left, you will see a small cement "monument" leaning over and on it you will see a bronze circle showing data on it. I have a pic and hope I can find it for you. The BM's are part of the survey system that occurred many years ago... and, indeed, continue today. TTC