a practical illusion turned a big skylight shaft into a grid of smaller ones in this dining room ceiling. Using one skylight was cheaper and easier than building many smaller ones, and the grid design softens the light and reduces heat buildup. It all started with a 4-by 7-foot skylight mounted on a built up curb atop a flat roof. The existing 2-by-8 joists were left intact, and 2-by-6 blocking was added on top. Centered beneath the skylight, a 613-inch-wide spine was boxed in with 2 by 8’s and 2 by 6’s and capped with plywood. The spine divides the flanking spaces into 13 1 2-by 16-inch shafts, which open to the skylight. Gypsum board painted white lines the shaft, and three downlights in the spine focus on the table to provide illumination in the evening. Designer was William Smart of Carter Cody Associates, Palop Alto, for Shirley brooks of Belmont. California.