Here are a pair of polish helmets, a Lancer cap and a mounted Fireman's helmet. They date from the 18760's.

What unit would of worn the Lancer helmet seeing there was no Poland in  the 1870s, Poles depending on where they lived  serving in either the Prussian, Austrian or Russian armies and of course wearing the national uniform of these countries. Same with the fireman helmet, these being of a different design related no doubt to these countries.