It is a Smith & Wesson 3rd model Single-action .38 (S&W), blue, with a 6 in. barrel, target front and rear sights and target stocks.
It was shipped to H. S. Gilbert in Cincinnati, OH in November of 1899. One of the blurbs that I found on Google stated that H.* S. Gilbert of the Louisville Revolver Club used a S&W SA .38 with a 6 in. barrel. Another one stated that he set the club record for 20 yds. with a pistol of that description.
In 1905 Henry Gilbert was secretary of the Louisville Revolver Club.
This has the potential to be one of those "Best Single Pieces" at a gun show; but I need a lot more information.
Books
* Pretty sure that the H is for Henry.