Looking for information/author of painting

You COULD clean it up a little yourself - unless it's of great sentimental value, it wouldn't be worth getting a professional in - but in your place I'd just give it a wipe over with a soft brush to remove surface dust every now and then.  Because assuming this is varnished, and it probably is, the only way to really clean it would be to remove that varnish (which would take cotton buds, Turpentine, and great patience): and that's not something to be doing unless you've been trained; you could (assuming you have any) try cleaning one of your own paintings.... if nothing else, it would teach you that it's a skill; I've done it, but it's not the most enjoyable of processes - and I wouldn't dare do it to someone else's painting. Alan goes even lower on the value than I did; there's only one way to find out who'd be right, and that's to put it up for sale, which you don't want to do.  Everything depends on who's in the auction room on the day.   Summarizing both of our thoughts, I think: your painting is best left as it is, because you enjoy it; if one day you want to sell, or your descendants do, someone else can have the decision about cleaning it or leaving it well alone.  I've got to say that a really professional clean could do it the world of good - but there's no hurry to do that; so long as no one in your house smokes, and it's not in a room subject to condensation from the cooking-pot - it's had about 100 years to get in this condition, another 100 won't hurt.  Your attitude to it is the right one.