lías anybody noticed the niiniature fort ut tbo top of 13lack well's I.-sland, to the north uf the Luuatic Asylum ? It is thu work of an insane man, who lias spent half bis life upon it. lío lost bis niind in Mexico, or some wbero elsu vvbore h:gh privates wcre in demaud, and just eeóaped beiug Mr. Anustroug, or Mr. Parroít, or Mr. Whitworth, by going oruzy. Guutiery was wbat uiled hiw - aud fortifioatioos, He was found to bo quita hopeless, and obodicat to bis monomanía, they gave biifi intrenching tool.=, aud told bim to forti ly the island. Ho touk tho georaphical and g&'logical beariugs with the aecuracy of a West Pointer, and eoneluded that any attack upon it would come fiom the Sound. So lie devisad a soa ooust battery, vvith bomb-proof approachcd by a dike with sluices aud gates, and mouuting heavy ordnauoe, Tbyre never was a more patieut woi-kei' í'or humanity or patriotism tbau this pooi' addled head ! Nubody o'se being insane upon the same poiut, he conld get no assistauco. AU the other raouoinauiacs had oil on the brain, or poetry, or capital punisbment, or negr.) uflrage, nnd wero quito ís devoted and zealous as he upon their several claims. So the oíd soldier, with a long s'gb, anda brave heart, tiokup bis singlo shovel and oomiuouced to build the whole fort by hiinself. He wheeied banow after barrow of earth into the sen, tuggiug frorn raorn ing till night, until at last bo raiaed a narrow cauaeway frorn ihe uia;u land to a rook at tho end of a l"g sand bar. With pubbles aud sbells aud stone from tho river, walled this causewny until it became permanent. All this was not a moutb's or a year's work ; year alter ye:ir prissed over his gray hairs, but he kept on wbeeling, wheeüng ! The great city on the greater island required piotection, aud he was making itaegis. So he went on like the uien who threw up the Charleston redoubts, and for fear tbat he urgbt be late to his tank, ho left his bed in the asylnm altogether and built hiuiself a hut closo to bis placo of labor. Hert) ho slept and dwelt 111 the company only of his afsuring conscience ; aud wben at last his patb was done, ho set to vvork at his fort. The rcsult of all thoso years is before us. His battery is sodded gieon, with parapet, berm, ditch, magazine, ievotinents, abattis, and it mouuts mock, or Quaker gnus upon carriages of capital coDstructiou, looking up the sound toward Heil Gate, like real arbiters of dominion. The old lunatie is worn and fiiling, but he iw not saiisfied. His fort is dono but nut his whole duty. So ho has projected a wator-battery and soa-wall around tho ontiie island, and ineans to bring to bear upou lt uil the kuowiedge of Vaul)au and Todleu. Wheu the island is impregnable, he will wrap lus mantle about him aud die at his battery. i Fur the truth of all this Btory, lttj anybody passing up East river look upon the island tij), and see an old ma;) ditching and building, aud the litile fort close bj him bristüng with pop-guus.