Arc "Welding" of any kind was rare before WWII ship building forced changes in riveting techniques.
And they learned a lot then, but in 1908? I suspect the angle iron attachment is a "later detail" added with no QA and probably no NDE and probably no welding procedure or preheat or confirmed electrodes.
The round surface in your photo doesn't look like "steel" but has the coarser "feel" of a cast iron column. What does the rest of the column look like? End pieces? Caps? Ornamental ends or flutes or decorations? Once a cast mold is made, the old guys usually added embellishments and decorations to mimic stone columns if they could afford it. The extra decorations don't cost much after the first mold is carved.
Welding to cast iron can produce a "sticky joint" but you really don't know how strong it is.
If visible, treat the column like an ornamental piece, and remove the weld. Do something else to replace the suspect joint. If invisible, replace the column and salvage the cast iron - others WILL want it in other projects.