They are iron ( unlikely steel at that age ) identified by the density match to iron. The reddish color that looks like granite is rust on a pitted surface. Pig iron ( high carbon and silicon ) or wrought iron ( more or less pure iron ). An unusual shape for either as far as I know. My guess is that they are raw material intended to be made into something. A ...
I use water-based (project or panel) adhesive on foam board or any plastic which the solvent will dissolve, or where cleanup of spills is a concern. Solvent-based (heavy duty) for almost everything else. It dries faster and holds better.
If it is at all possible, you make sure you can see the other side before you drill. In some areas fishing wires into an unopened space is considered concealed work and must be done by a master electrician.
That said, a few tricks I've seen used:
There are many types of electrical toner. I don't know the name of the one you want for this, we just called it ...
Water based adhesives have the following disadvantages:
Slower drying than solvent based adhesives
Susceptible to freezing at low temperatures.
Lower water resistance than solvent-based products.
On the other hand, disadvantages of solvent based adhesives:
Cost – solvent based adhesives are more expensive than water-based adhesives.
Cleaning: Residues ...
For connecting tread to stringer, a piece of flat bar welded on to make a bracket (instead of angle).
For risers (if needed) the the top end of the riser is typically held in a groove in the underside of the tread, and bottom end attached to the back of the other tread,
Stringers are often C-section beams (not flat bar).
If the wall is rectangular and not trapezoidal, it is typically built on the floor (trapezoidal is too, but a slightly different process). The header for the window is either sized by the engineer or it will be listed in the code book.
When the wall is finished assembled is is taken to the layout line on the floor where it is to be permanently located and ...