TIN ROOFS AND FIRE PROTECTION.

TIN ROOFS AND FIRE PROTECTION.

在铁皮屋顶绝不是一种有效的手段of fire protection to buildings, they are still infinitely superior to slag roofing, as was recently shown after a test at Indianapolis. In that city two small low buildings were put up, one with a tin roof; the other, forty ft. off, with a roof of tar and gravel roof. The walls were brick and inclosed a space 8x12 ft. The supporting timbers were 2x4 in. and supported 1-in. yellow pine sheathing. Each building was alike; but one roof was finished with a standing tin roof, with a gutter running across the end, along which a fire was built. I he two sides had low battlement walls, and the fourth edge of each roof was carefully finished. The tar-gravel roof had a covering of three-ply No. 2 felt and was laid with 80 lbs. of melted pitch, with a heavy coat of gravel. The sides of each roof where the tire was to be lit had three-and two-in. wrought iron pipes bent in a half-circle firmly imbedded in the ground at one end. To tile other end was fastened corrugated iron, which was to act as a shield to deflect the flames on the roof tops. Below these sheets was a space between the walls of 1 ,½ ft.—enough to admit of the air keeping up a brisk fire. Light inflammable material was filled in between the two structures, and was liberally drenched with kerosene, care being taken that neither roof received any. The fire was built alongside of the structures, and the deflecting shields threw the flames directly upon the two roofs. The fire was lit at .5:47 p. m., at which time a slight wind was blowing from the shields towards the buildings, in such a way as to carry the flames across their surface At 5:51 the flames leaped across the building with the tin roof and caught on a building with a tar roof 40 ft. front the burning building. The tar and gravel roof sent up a dense black smoke To make the test more severe, openings were made under each building on the left-hand side; at the point nearest the fire breaks were made in the wall of each, to admit a free current of air, while other openings were made so as to allow the air to circulate freely beneath the roof-timbers. Ilv 0:7 the gravel roof was all alight, and a little before 6:52 small jets of flame shooting through the cracks in the sheathing showed that the whole building was on fire. The flames were then allowed to die down; the tin roofing was ripped off, and the sheathing boards on the targravel were opened up. Under the former the beams were only charred, while those of the latter had not only been on fire, but needed only a little more time within which to burst into flames which would have destroyed the whole building. The lesson to be learned from the test was that when, as at Indianapolis not long before, a defective flue started a fire in a building with a tar-gravel roof, nothing could check it and the fire must spread if there were any inflammable buildings round. At Indianapolis, where a roof-surface of over fioo.ooo ft had been burned over, the tar-gravel roofed buildings were ruined, and more would have been burned, if they had not been covered with snow. One building alone stood up for four hours against the flames and that was covered with tin. It withstood the attack of the flames from the other type of roofs covered with gravel and the regular 80 ft. of nitch to the square. Over tft) barrels of pitch, therefore, and 300 rolls of tar paper had caused the flames to beat in vain against this tin-covered roof.

在铁皮屋顶绝不是一种有效的手段of fire protection to buildings, they are still infinitely superior to slag roofing, as was recently shown after a test at Indianapolis. In that city two small low buildings were put up, one with a tin roof; the other, forty ft. off, with a roof of tar and gravel roof. The walls were brick and inclosed a space 8x12 ft. The supporting timbers were 2x4 in. and supported 1-in. yellow pine sheathing. Each building was alike; but one roof was finished with a standing tin roof, with a gutter running across the end, along which a fire was built. I he two sides had low battlement walls, and the fourth edge of each roof was carefully finished. The tar-gravel roof had a covering of three-ply No. 2 felt and was laid with 80 lbs. of melted pitch, with a heavy coat of gravel. The sides of each roof where the tire was to be lit had three-and two-in. wrought iron pipes bent in a half-circle firmly imbedded in the ground at one end. To tile other end was fastened corrugated iron, which was to act as a shield to deflect the flames on the roof tops. Below these sheets was a space between the walls of 1 ,½ ft.—enough to admit of the air keeping up a brisk fire. Light inflammable material was filled in between the two structures, and was liberally drenched with kerosene, care being taken that neither roof received any. The fire was built alongside of the structures, and the deflecting shields threw the flames directly upon the two roofs. The fire was lit at .5:47 p. m., at which time a slight wind was blowing from the shields towards the buildings, in such a way as to carry the flames across their surface At 5:51 the flames leaped across the building with the tin roof and caught on a building with a tar roof 40 ft. front the burning building. The tar and gravel roof sent up a dense black smoke To make the test more severe, openings were made under each building on the left-hand side; at the point nearest the fire breaks were made in the wall of each, to admit a free current of air, while other openings were made so as to allow the air to circulate freely beneath the roof-timbers. Ilv 0:7 the gravel roof was all alight, and a little before 6:52 small jets of flame shooting through the cracks in the sheathing showed that the whole building was on fire. The flames were then allowed to die down; the tin roofing was ripped off, and the sheathing boards on the targravel were opened up. Under the former the beams were only charred, while those of the latter had not only been on fire, but needed only a little more time within which to burst into flames which would have destroyed the whole building. The lesson to be learned from the test was that when, as at Indianapolis not long before, a defective flue started a fire in a building with a tar-gravel roof, nothing could check it and the fire must spread if there were any inflammable buildings round. At Indianapolis, where a roof-surface of over fioo.ooo ft had been burned over, the tar-gravel roofed buildings were ruined, and more would have been burned, if they had not been covered with snow. One building alone stood up for four hours against the flames and that was covered with tin. It withstood the attack of the flames from the other type of roofs covered with gravel and the regular 80 ft. of nitch to the square. Over tft) barrels of pitch, therefore, and 300 rolls of tar paper had caused the flames to beat in vain against this tin-covered roof.