There is a hoop skirt manufactory in this city which weekly turns out 24,000 ladies' skirts, employing for that purpose 500 hands, 180 sewing machines, and not less than a tun of steel. Hoop skirt making is a science, and one on which patient study and exquisite skill have been bestowed in the several departments of the fabrication, till by successive improvements an article of dress has been produced which is thought to be favorable to health, while it conduces to comfort and beauty. Various materials have been employed to give the required degree of flexibility to the skirts, to enable their wearers to sit upon them, and pack them to the smallness of compass frequently required, without affecting their elasticity and capacity to again spread themselves to the full extent and graceful form when raised to an erect position. We believe, however, that the rotundity of spread is now given to this general favorite of female apparel by very thin steel springs, so prepared and intertwined with the stiffened fabric of which they are principally composed as to give them these characteristics.