Smith and Wesson Chief's Special
Frank,
Folks who know more than I do about Smith and Wessons will no doubt chime in, but just to get you started.
Your uncle bought an early version of the Chief's Special, so called because it was introduced at a convention of the American Association of Chiefs of Police. I think that's the correct name. Most models came with a two inch barrel, but some like your uncle's, had a three inch barrel. 36 is the model number, the 1 indicates it is the second issue (the first having no number after the "36." The "J" in front of the serial number indicates the frame type, i.e., S&W's small frame, five-shot revolvers.
CTG stands for "cartridge," and indicates that the revolver is chambered for the .38 Special cartridge. The .38 Special was the most popular revolver cartridge for law enforcement units until agencies began the transition to high capacity semi-automatics.
You might visit Gunbroker.com and GunsAmerica.com and do a search for Smith and Wesson 36. There are lots of listings, with prices in the $250 and up. 'Way up for pristine guns.
Since apparently neither your nor your uncle are "gun guys," I recommend you take this to a knowledgeable gunsmith (probably NOT the guy behind the gun counter at WalMart) to have the gun checked out to be sure it is safe. Then get some instruction/training in safe gun handling for your uncle and yourself if you intend to shoot it.