Your photograph did the trick. I can now identify your revolver.
You have a Smith & Wesson .38 Single Action, 2nd. Model. These were made between 1877 and 1891, within a serial number range running from 1 to 108,255. Your revolver is a late one at serial number 102,281, and probably was made during the latter 1880's.
(As an aside: Under U.S. Federal law and in many other countries it is classified as an "antique" and as such is exempted from statutes governing firearms.)
It was one of the first revolvers chambered to use the then new .38 S&W cartridge. Modern smokeless powder ammunition is available, but should not be fired in a gun of this age.
The cylinder holds 5 rounds. Standard barrel lengths were 3 1/4 or 4 inches, although some were made with longer lengths. Standard finishes were blue or nickel-plated, with nickel being the more popular. The stocks are made from black hard rubber, also know as "
gutta percha." Be careful how you handle them, as they become brittle with age. That last patent date is May 11, 1880.
Given this gun's history within your family, I suggest that you get it "lettered." To do so you will need a snapshot of the gun, a full description including the serial number on the butt, and a check in the amount of $30.00 made out to Smith & Wesson. In exchange the company's historian, Roy G. Jinks, will research the original records (which are not computerized by the way) and send you a letter containing the details of what he finds.
This comprehensive document will contain an overview of the model’s history, followed by the details of your particular gun. This usually includes the caliber, barrel length, finish, and the exact date it was shipped from the factory, and to what distributor or dealer. If there are any special features they will be listed too. This information is often invaluable to both you and future generations.
Additional information on a historical letter will be found at the Smith & Wesson company website at:
http://www.smith-wesson.com/webapp/...catalogId=11101&content=25301§ionId=10504