The best mixture of asphalt is to mix with the asphalt ten per cent. of coal tar, and twenty-five per cent. of sand; and use while hot to form a cement for bedding brick for damp cellar bottoms. Sylvester's Process for Repelling Moisture from External Walls. The proportions are for the first: Mix three-quarters of a pound castile soap with one gallon water; second, mix one-half pound alum with four gallons water. These substances to be perfectly dissolved. The walls should be clean and dry, and the temperature not less than 50° Fah. when the composition is applied. Put the soap wash on when boiling hot with a flat brush, and do not work to a froth. Let it dry twenty-four hours, or be perfectly dry. Then put on the alum wash at about 65° Fah. for the mixture, and should dry perfectly before putting on the soap wash; and this is to be repeated alternately until the wall is impervious to water. The alum and soap forms an insoluble compound. CHAPTER VI. Front Vaults. An important part of construction to store buildings in our large cities is the excavation and building of vaults under the streets, or under the sidewalk and area. See Abstract of Laws in reference to vaults, chapter iii. These vaults are usually lighted by setting thick glass in iron frames over the area part-the best are those made by J. B. Cornell—and the sidewalk is covered with arched brickwork, and on top of this stone flags, or covered with large flags of stone, resting on a girder or beam supported by columns where necessary. The best stone is the North River bluestone in use here, and is generally ten inches thick. Where granite has been used for the purpose it wears so very smooth as to become objectionable. The joints of the stone are caulked with oakum, and filled with pitch and cement. See illustration 37. The top of walls (A) are usually coated with asphalt cement. The outside retaining wall is usually two feet six inches to three feet thick, with a hollow space of two or three inches, and an inside eight-inch wall. where the walls and vault are extended out under the street beyond the curb. For this arrangement there is generally required a special permit. Vaults under sidewalks are sometimes carried to the depth of twenty-five feet below line of curb, and make two stories extending under sidewalk; the outside retainingwall is usually of stone. TABLE OF STRENGTH OF STONE FOR VAULTS, PLATFORMS, GALLERIES, BAY-WINDOWS AND OTHER PURPOSES. Transverse Strength of Flagging. - W, width of stone in inches; T, thickness of stone in inches; D, distance between bearing in inches. The Breaking Load in Tons of 2000 lbs. for a Load on the Thus a blue stone flag, 100 inches wide, 6 inches thick, resting on a bearing, or on beams, 72 inches to centres, would be broken by a load resting midway between the beams or support x .744-37.20 tons, breaking load. 100 x 62 It is best in using these tables not to exceed a working load of one-quarter to one-sixth the breaking load. Over vaults to warehouses allow a load of 600 pounds per square foot, and 500 pounds per square foot for stores. TABLE OF EXPERIMENTS ON BRICK. New Jersey, unburnt... 406 468 13,000 15,000 Best Hard North River Pavers (half)... 38,000 55,000 2375 3437 North River whole Brick not injured at. ...... 60,000 .... Adamantine Press Cis-brick, crushed at 90,000 lbs., being at the rate of 2,800 lbs. on the square inch. RULES OR TABLE FOR CALCULATING THE WEIGHT OF Calculate the weight of wall per superficial foot of surface, and deduct only one-half of window openings. 8-inch brick wall, weight per foot........... 77 pounds. NEW YORK LAW IN REFERENCE TO LOAD ON FLOORS. Hardware Store, weight on square foot floor surface.. 350 to 600 lbs. After making calculations of loads in ten dry goods stores, they were found not to be loaded to exceed 180 pounds per square foot on the basement or first and second stories, and much less above. Mensuration of Superfices. - Simple rules for calculating superficial surfaces of different shapes: Triangle-Multiply base by perpendicular and divide by 2. between them; divide by 2. Parallelogram-Base by perpendicular. Trapezium-Diagonal by one-half sum of perpendicular circle. Circle-Diameter 2 by .7854. Circle-Circumference by radius, divided by 2. Ellipse-Transverse axis by conjugate axis by .7854. Cylinder-Length by diameter by 34. |