The Boston hip is the best. Each course is brought at its upper or nailing edge to within 2 inches of the hip line. A small strip of slate then finishes this off by fitting to a mitre cut made on a slate set parallel with the line of the hip. These hip slates have the lower corner of their butt ends on a line with the next lower course, and they are lapped with the opposite hip slate and made tight with roofing cement. [Illustration: SLATE ROOF] Hips may also be finished by bringing each course up to the hip line, and mitring them with the opposite courses on the other side of the hip. Valleys should be lined with 16 ounces copper, 4 pounds lead, IX tin, or a prepared roofing roll weighing 37 pounds per 108 square feet. Measuring from the centre of the valley to the edge of the slate along the valley, this distance should be 2 inches at the top and increase ½ inch in every 8 feet length of valley, to widen it out toward the bottom. The flashing should extend up under the slate on either side about two-thirds the width of the slate used. If 8-inch by 16-inch slates are used, this means that the distance should be about 5 inches. If the slopes of the two intersecting roofs are different, and there is a chance that the volume of water sweeping down the larger and steeper incline may be forced up under the slate at the valleys, the metal lining should be crimped up (inverted V-shape) at the centre, 1 inch, to form a little dam against the rush of the flood. [Illustration: SLATE DETAILS] Flashing used against chimneys, dormers, or other vertical walls should be bent up 4 inches and extend into the slate courses 4 inches. All vertical flashings against masonry should be cap-flashed and made tight with elastic cement. The cap-flashing should extend down over the flashing 3 inches, and be inserted into the masonry at least 2 inches. [Illustration] Sometimes the closed valley is designed for slate roofs, in which case the valleys must be rounded out with the roofing-boards, blocked to position. The slate courses should be carried around this curved valley, but each course in the valley should be covered with flashing just under the lap of the course above and extend up toward the nails. TILE ROOFING Preparations of the roof for the laying of tile should follow similar lines described for slate roofs. Over the roofing-boards should be tacked asphalt roofing felt, weighing not less than 30 pounds per 100 square feet and lapping 2½ inches. The valleys should be lined with this felt, running the entire length, and then the flashing metal placed on top, secured with clips at intervals. The width of the valley metal should not be less than 24 inches, and both edges should be turned up ¼ inch the entire length of the strip. The felt covering the main surface of the roof should lap over the valley metal 4 inches.