Welcome to the Forum. Your Model 1 1/2, 2nd Issue revolver in 32 Long Rimfire, and is very nice with what may be original factory engraving. At least the style is correct, but many were engraved by the distributor post-factory, so a detailed inspection would be necessary. More close-up pictures might help our engraving experts determine authenticity. Cannot tell for certain, but the trigger and hammer look like they have been plated?
If so, this might be an rare full-plate gun that has been identified as original factory work in the past, but also common with replated guns after non-factory engraving. That revolver would have shipped around 1873.