Pantiles (fig. 3b) were first used in Flanders, and resemble the foregoing in shape and size, differing only in the cross-section, which is of an undu latory or twisted shape. A small tongue, or lip, is bent from the under side, by which it is hung upon the lath. The tiles are set so as to overlap in a lateral direction, but longitudinally the lap is slight; so that they furnish a much lighter covering than plain tiles. With a more pleasing effect to the eye, there is much less weight, and decidedly inuch less pro tection against cold, with greater liability to damage from wind-storms. They are set either dry or in mortar, but pointing upon the inside with liine and hair has been found very advantageous in damp climates. A variety of pantile known as the Bridgewater tile is useful for common pur poses. Roofing in the last-mentioned styles is performed upon the princi ple required for the gutter tile. As the tiles not only touch in each course, but also hook over one another, the joints are rendered tighter.
Rebated same principle is followed when the rebated tile is used, two examples of which are exhibited in Figures 4 and 5. The tile shown in Figure 4, which was invented by Courtois of Paris, is square in form, ro3/4. inches on each side, having two edges projecting upward (fig. 4b) and two downward (fig. 4c), these edges being 3/4. of an inch in breadth and height. There is a lug, also, for suspension (fig. 4r). These tiles require a distance between the laths of about 6 inches, as they present square surfaces of only 9Yt inches when set in the roof (fig. 4a'). The thickness of the tile is of an inch. The rebate tiles shown in Figure 5 are also of French origin, and were exhibited, with numerous others, at the Exposition at Paris in 1867. They have rebates on all four sides; so that if the roofing is carefully done it is almost impossible for snow or rain to penetrate even when no mortar is employed.
Among the other styles of this kind of roof-covering, the terro-metallic tile has a projection at the back to fasten upon the laths as a substitute for pegs. Italian tiles have occasionally been used in England for many vears; they are slightly curved, fitting easily into one another, have a horizontal inclination across the upper part, to prevent the entrance of rain, and are provided with vertical rolls, either wide or narrow. The chief objection to tiling in damp climates is the rapid absorption of moist ure, which, communicated to the laths and rafters beneath the tiles, soon causes the plaster to deteriorate.
In the United States plain tiles are usually of an inch in thickness, Ioj< inches long, and 6;4' inches wide, weigrhing from two to two and one half pounds each. They are generally hung upon the lath by two oaken
pins inserted into perforations made in the tile; they have grooves and fil lets on the edges, so that there is little necessity for overlapping, as the o-rooves conduct off the water. Pantiles are used 14y„ inches by 6 size. Semicylindrical tiles are named " crown," " ridge," " hip," and " valley " tiles, the name indicating- their purpose. Siding tiles are sometimes used instead of weatherboardingr, and are made orna mental, being often decorated upon the surface with crenated edges.
Slate in thin sheets has recently become very popular as a roofing- material. The varieties found in England are excellent in quality and varied in appearance. That of a blue-gray tint is esteemed as the best, and answers to a sharp stroke with a ring like that from well baked pottery. Blue-green and green slates are good, and are admired for their coloring, those of a light gray tint being generally stony, while those of the darker shades, though cutting freely, decay rapidly by absorption of moisture. The poorer and more absorbent qualities are smooth and greasy to the touch, the best being hard and rough. Two inethods—dis tinguished as the German and the English—are practised in roofing with this material.
Diagonal the German method (pl. 7,11g. as " simple diagonal roofing "—the slates are nailed in diagonal rows, sup ported on boarding in such a manner that each individual row, as well as each slate of which it is composed, is made to overlap. The upper and the lower courses—that is, the eave-course and the ridge-course—run horizon tally. The nails by which the slates are secured are driven only through the parts that are hidden. The slates are cut straight—at least, on two sides —though they are not of equal breadth throughout.
Double English method—known as " double roofing" —corresponds to the double roofing with plain tiles. The slates, generally 24 by 15 inches, are made to meet one another flush, and the first course overlaps the second past the point where the third begins. The courses being here set horizontally, the wooden boarding may be replaced by laths. Figure 7 shows the form of roofing with wooden laths, and Figure 8 that with iron laths. The pair of nails required for each slate in the case of wooden laths are to be driven as deep as possible, but so that they shall be covered by the next slate. Sometimes, as the Figure shows, an additional nail is driven at the upper eclg-e; so that only half the head overlaps.