Welcome to the Forum. Actually, it is a bottom-break, but the term most often used for this type of revolver is Tip-Up. You have a Model 1 1/2, Second Issue, 32 rimfire that most likely shipped in 1869 (I think Ed's date is a slip-up with the keyboard). One cannot be certain about the originality of the finish with only one image, but is is possible that you might have an original finish Model 1 1/2. Standard barrel length was 3 1/2", but the company also offered this model in a 2 1/2" length.
There were over 127,000 Model 11 1/2s made and remarkably, many survived in good mechanical condition. If upon close inspection, your revolver turns out to be original, it is worth a fair amount of money. I would offer a different opinion on the value than Ed, based on auction pricing and Supica's SCSW4. If it grades as Excellent, you have a $700 gun, but there are not many collectors who specialize in this era S&W anymore and the next one that goes up for auction could sell for Ed's price, due to a volatile market. One problem is that these are not gaining value today and may be slipping some in the market. Another issue is that there is absolutely no ammunition manufactured for this gun today and it is about impossible to find any reliable old ammunition out there to use from any source.