Help to ID this watch

I know there are a few folk on here that are seriously into watches (horologists?), wonder if any of you can shine some light on this one.
It was my grandads, pretty sure it’s 1920s and it works.
On the face above the second hand it says “shockproof” and at the bottom outside the border it says “Swiss made”. On the rear it says ” nickel chrome”, “Swiss made” and then the numbers 639299 I think.
I’d be grateful for any info. re. watch or any pointers where to look or who to ask.

[/url]IMG_20160220_094808464 by pmacm2007[/url], on Flickr[/img]
[/url]IMG_20160220_094847559 by pmacm2007[/url], on Flickr[/img]

Same typeface and similar shape? They’re erring towards Arctos/Weber & Aeschbach, but I can’t see anything similar with a google image search…
http://forums.watchuseek.com/f11/mysterious-lady-1920s-gents-watch-cal-felsa-158-a-995902.html

Ok thanks for that, maybe not but gives me another seam to mine.

Pop the case back off and see if the movement is named?

CZ I did’nt think I had the bottle to do it but I did, I popped the back off and was met with the most beautiful mechanical micro world, all shiney and ticking away.
No makers name as such but check out those blue lined engraved winged discs, they do look familiar, but from where?, let the hunt begin.

[/url]IMG_20160221_182332155 by pmacm2007[/url], on Flickr[/img]
[/url]IMG_20160221_182301048 by pmacm2007[/url], on Flickr[/img]

It’s Rotary isn’t it, it’s got to be, I’m 99% sure, would anyone concur.

any chance of a close up pic please

Pretty sure that is a Rotary movement. They introduced the winged wheel logo in 1925 so that seems to fit your time line. Looks like this one?

http://www.poshtime.com/bigpic-arc.php?id=495.123
Rapid edit:
Gold version but no maker. That number 12 looks fairly unusual.

I think we have the right watch. The case that you have is a plated brass one compared to the silver one that I found and the gold one on poshtime. It looks to be a very robust watch so no surprise it is still working. A quick service (lube the bearings) and that should just keep on going. Nice family heirloom.

Yep, think we’ve got it nailed down. A huge thanks to all who contributed, once again this place turns up trumps.
Mrsfry these should be better quality piccies, the lights not great but there’s more detail than in the phone ones.

[/url]001 by pmacm2007[/url], on Flickr[/img]
[/url]003 by pmacm2007[/url], on Flickr[/img]
[/url]005 by pmacm2007[/url], on Flickr[/img]
[/url]004 by pmacm2007[/url], on Flickr[/img]