There is not a pleasanter place in the world for a summer residence than Blackwell's Island! The chief edifices are substantial, and the grounds are laid out with exceeding care. The water-scape is delightfully invigorating, and the sojourners at this watering-place are not of that transient class which one finds at Nahant, Newport, and other pet resorts. Indeed, it is usual to spend from six to eight months on the "Island," and one has the advantage of contracting friendships which are not severed at the first approach of the "cold term"--for the particulars of which "cold term," see that funny old _savant_ of Brooklyn Heights, who has a facetious way of telling us that it has been raining, after the shower is over.--Bless him! Such institutions as "Blackwell's Island" are godsends to the _literati_. A poor devil of an author, who has a refined taste for suburban air, but whose finances preclude his dreaming of Nahant, has only to mix himself up in a street fight, or some other interesting city episode, to be entitled to a country-seat at the expense of his grateful admirers! Owing to a little oversight on his part, the author of this veracious history took a passage for "Blackwell's Island" a trifle earlier in the season than he had anticipated; and it is at that delightful region these pages are indited. But the Tombs--heaven save us from that! There are many pleasanter places in New-York than the Tombs; for that clumsy piece of Egyptian architecture--its dingy marble walls, its nail-studded doors and sickening atmosphere--is uncommonly disagreeable as a dwelling. Many startling tragedies have been enacted there--scenes of eternal farewells and lawful murders. I could not count on my fingers the number of men who have entered its iron gates full of life, and come out cold, still and dreadful! It was here that Mortimer was brought. Within, all was sombre and repulsive. Without, there was hum of voices, and the frosty rails which ran in front of the prison creaked dismally as the heavy freight cars passed over them; but these sounds of life were not heard inside. The cell of Mortimer and its occupants, the morning after his arrest, presented a scene of gloomy picturesqueness. Through a grated window, some six feet from the stone floor, a strip of sunshine came and went, falling on Mortimer, who leaned thoughtfully against the damp wall. The room, if we may call it one, was devoid of furniture, with the exception of a low iron bedstead, whose straw-stuffed mattress and ragged coverlid suggested anything but sleep. Daisy Snarle was standing with downcast eyes near the door which a few minutes before had closed on its creaking hinges, and outside of which the jailor stood listening.