I have an old pistol, it says EIBAR-1924 under a screw hole on the right side it has on the barrel .38 LONGCTG?

On top of barrel it says REVOLVERS-DREADNOUGHT below that is has PATENTS AVRIL 1917 11 JUNE 23 JULY 1915, between the handle and trigger on the bottom it says SPAIN, also there is a hallmark right before the barrel starts it looks like a crown over a shield with a X inside the shield just to the right are the letters PN. It was her dad's when he was still alive and we just found it wrapped and hidden in a crawlspace in the farmhouse, i know he collected guns and had alot of rare ones but this one i cannot find any info on or value. Any help?