The weight of snow will be in proportion to the depth it acquires, which will be in proportion to the rigor of the climate of the place where the building is to be erected. Upon roofs of ordinary inclination, snow, if deposited in the absence, of wind, will not slide off; at least until after it has acquired some depth, and then the tendency to slide will be in proportion to the angle of inclination. The weight of snow may be taken, therefore, at its weight per cubic foot (8 pounds) multiplied by the depth it is usual for it to acquire. This, in the latitude of New York, may be taken at about 2 1/2 feet. Its. weight would, therefore, be 20 pounds per foot superficial, measured horizontally.