That is the 1903 Colt Pocket Hammer in Colt .38 ACP "Rimless Smokeless". It was a shortened version of the 1902 Sporting pistol. Yours was probably made in 1907.
Sadly not a lot of value left in that one. Not a gun that is in demand in that condition. I would say in the $250/350 range depending on how it checks out.
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