NUMBER OF SLATES PER SQUARE ========+=========+=========+=========+=========+========= Size |Number of| Size |Number of| Size |Number of Inches | Pieces | Inches | Pieces | Inches | Pieces --------+---------+---------+---------+---------+--------- 6 × 12 | 533 | 9 × 16 | 246 | 14 × 20 | 121 7 × 12 | 457 | 10 × 16 | 221 | 11 × 22 | 138 8 × 12 | 400 | 9 × 18 | 213 | 12 × 22 | 126 9 × 12 | 355 | 10 × 18 | 192 | 13 × 22 | 116 7 × 14 | 374 | 11 × 18 | 174 | 14 × 22 | 108 8 × 14 | 327 | 12 × 18 | 160 | 12 × 24 | 114 9 × 14 | 291 | 10 × 20 | 169 | 13 × 24 | 105 10 × 14 | 261 | 11 × 20 | 154 | 14 × 24 | 98 8 × 16 | 277 | 12 × 20 | 141 | 16 × 24 | 86 ========+=========+=========+=========+=========+========= In Table XII is given a list of the different colors of slate used in the Eastern and Middle States, the quarries from which they are obtained, and the cost of slate, labor, etc. per square, pertaining to each variety. The prices in the table are based on the 8 in. × 12 in. or 9 in. × 18 in. sizes, thickness five to 1 inch, and for quantities of not less than 50 squares. The cost of labor, etc. being based on current prices in the aforementioned territory. Slate ¼ inch thick cost about 20 per cent. more than the five to 1 inch for the material, and about 5 per cent. more for laying and freight. Slate ⅜ inch thick cost about 45 per cent. more than the five to 1 inch for the material, and about 15 per cent. more for laying and freight. When copper nails are specified obtain current prices. TABLE XII