Re: Colt 38 D.A.
The gun is a Colt Model 1889, chambered for the .38 Long Colt cartridge. It is in rather poor condition, with chipped grips and missing the end of the ejector rod (not just the removable head).
It was made in 1892 and is an antique under Federal law. There are no cylinder notches because that gun used the same system as the Model 1878, where the hand both turned the cylinder and locked it in place.
Over 5000 were ordered by the U.S. Navy, but that one is a civilian model. Those guns are delicate and are often found with parts broken or badly worn.
Value, in that condition, would be around $300, possibly even less if the gun is not functional. If there are any railroad markings, it might be of intrest to collectors of railroad paraphernalia.