Considering the wonderful ease and expedition with which fugitives may be recovered by law, it would be very strange if mistakes did not sometimes occur. _How_ often they occur cannot, of course, be known, and it is only when a claim is _defeated_, that we are made sensible of the exceedingly precarious tenure by which a poor friendless negro at the north holds his personal liberty. A few years since, a girl of the name of Mary Gilmore was arrested in Philadelphia, as a fugitive slave from Maryland. Testimony was not wanting in support of the claim; yet it was most conclusively proved that she was the daughter of poor _Irish_ parents--having not a drop of negro blood in her veins--that the father had absconded, and that the mother had died a drunkard in the Philadelphia hospital, and that the infant had been kindly received and _brought up in a colored family_. Hence the attempt to make a slave of her. In the spring of 1839, a colored man was arrested in Philadelphia, on a charge of having absconded from his owner _twenty-three_ years before. This man had a wife and family depending upon him, and a home where he enjoyed their society; and yet, unless he could find witnesses who could prove his freedom for more than this number of years, he was to be torn from his wife, his children, his home, and doomed for the remainder of his days to toil under the lash. _Four_ witnesses for the claimant swore to his identity, although they had not seen him before for twenty-three years! By a most extraordinary coincidence, a New England Captain, with whom this negro had sailed _twenty-nine_ years before, in a sloop from Nantucket, happened at this very time to be confined for debt in the same prison with the alleged slave, and the Captain's testimony, together with that of some other witnesses, who had known the man previous to his pretended elopement, so fully established his freedom, that the Court discharged him.