NEW ORLEANS, LA.- Whitney White Linen Night is more than the citys premier summertime cultural event. The annual art walk and outdoor celebration sponsored by the New Orleans Arts District represents the weaving together of two proud city symbols: Whitney National Bank and the elegant white cloth, a staple in wardrobes all over town. White linen is, of course, the traditional uniform worn across the South in the hot summer months. During the 19th and 20th centuries much of the linen was imported from Ireland. New Orleans, with its thousands of immigrant Irish, was a primary destination for the fabric. More breathable than wool or cotton, the beige fiber, bleached to the trademark snowy white, became a seasonal harbinger. You could always tell the coming of spring and summer in New Orleans when the white linen suits came out, and bankers would appear in them. says Wayne Phillips, Curator of Costumes and Textiles at the Louisiana State Museum. Linen was use