i'm not at all an expert in the watch field, poring through old stuff in my mother's house I found a watch of unknown origin.
it is an Ertus 17 rubis. The name of the maker is surmounted by an emblem that i found on another old pocket watch presently being sold on the net, but with a maker name like Horus.
The marking, however is the same as mine.
i'm interested in knowing more about the historical background of such type of watches (on the net some scant info seems to link Ertus to ww2 histories).
I have found it as quoted briefly in a german watch marking website (swiss maker pertusi from 1938)
On the italian ebay auction site I found the above quoted Horus watch with the very same trident style logo as mine