How beautiful! It looks like it's a vibrating shuttle type machine with a long bobbin. The pillar end resembles a Singer 28 and the needle end resembles an early White.
The tensioner is similar to the one on my White Rotary from 1926.
That domed cover is lovely and the decals are very 1910's-20's-ish - such beautiful condition! Lucky you! :)
You could probably download manuals for the Singer 28/128 and the White Rotary and between them, figure out how to make it run.
With just a little more luck, it will take a standard 15x1 needle, or a 15x1 needle scootched down a little bit in the clamp.