Now, i've got myself into troubles; i forgot these guys want to know everything
.
The Swedish Silva is just a coincidence; the name Silva is one of the oldest Portuguese family names.
I would swear this Joćo da Silva was from Braga, a city here in the north, but i don't remember where i have read this. Searching the name
per se is useless, as it is so vulgar as John Smith.
But in any case this little device is local handcraft. Amazingly, not necessarily being a 'sworn' apparatus, it does point (shamely) to North and, going out to the veranda i positioned it in the North ditrection and it indicated the right time over here: 5 pm it was.
Hard to tell its age; thirties or most possibly earlier. I wish i traced some other example i saw illustrated somewhere, which i think once happened.
Fernando