Thanks for posting the additional photos...still not entirely obvious how it was done though, is it?

I was hoping it was going to be the mechanically abraded version of Northwood’s technique but I should think you would see tool marks - Hajdamach says the wheel left a slightly irregular surface. Plus the outlines don’t look acid etched to me, it’s hard to tell without having a good look.
I think I agree with Sue with sandblasting, the areas not to be frosted masked with a resist. Then everything else engraved after. On the other hand, sandblasting wasn’t invented until 1870 and in America. McConnell says the bottom up type handle “...became standard practice at British works during the 1870s”. So there’s not much time for overlap if your jug with the older style handle is sandblasted (assuming it’s British and was decorated not long after manufacture etc).
There is a post here:
http://www.glassmessages.com/index.php/topic,32489.0.html that has some plates with a similar surface finish where the options seemed to be sand blasting or mechanical grinding. Probably won’t help though
