Hi mill3nia........What I believe your Grandfather had there is a ".32 Safety Hammerless". Some refer to it as .32 Lemon Squeezer or a .32 New Departure.
The concealed hammer with a "grip safety" design was a definate switch up for Smith! 1888 to 1937 (depending upon 1st, 2nd or 3rd model)....Given the partial seriel # you listed, it MAY be a 1st model (1888-1902)!
Story has it, that a youngster horse-assing around in those early Smith years latched onto a hammer style and gave it the old pull back and......kaboom. This might be what drove Smith to the Lemon Squeezer design.
Odds are a member here (or several) can shed more light on your old Smith. VALUE ....we all know how that goes, all depends on who would like to have it!!
Welcome to the forum!. Looks like a rather nice 32 caliber 1st model Safety Hammerless. They were also known as the New Departure or Lemon Squeezer. About 91417 of these little revolvers were made between 1888-1902. I would guess that yours left the factory in the early to mid 1890's. It uses the old black powder 32 S&W cartridge which is still available today in mild smokeless powder loadings. If you want to shoot it have a good gunsmith look it over first. I have a couple of these old S&W top breaks, as seen in my avatar, but none of them has any family hastory connected to them as does yours. Thanks for posting.