The heat of the sun is another destroyer of the house. It is death on paint, for it is forever baking it in the steam of the dew of the previous night, and when the body of linseed-oil is gone, the paint is no good. And it dries out the wood too much some days and spoils the jointing. It warps boards up and opens the mitred joints. It causes the wood shingles to crack and shrivel, so that when the next heavy rain comes the ceilings are stained by leaks. Tar for the roof and soft cements are caused to run out of place. Then, too, there is the deteriorating influence of the artificial heat inside of the house. The fireplace tiles are baked loose from their mortar beds, cast-iron dampers are cracked, chimneys are clogged with soot and catch fire, and thimbles which receive the smoke-pipe of the furnace are broken. But the heat from the radiator does much damage. It blackens the ceiling above it by hurling little particles of dust up against it; it warps and twists the wall-paper; it misshapes the doors and windows, and breaks loose the strips of veneer, and it often spills water over the floor to ruin the ceilings below. Added to all of the above depreciation is the natural wear and tear caused by the tenants. Floors are worn to splinters where they were of flat-grain wood; thresholds are thinned down, stair tread scooped out. Plaster is broken by moving furniture, and decorations stained by accidents of all varieties. Locks, hinges, and bolts are broken. Particularly is the mechanical equipment of the house subject to such deteriorating influences. Plumbing fixtures are broken, pipes are clogged, and joints made to leak through the corroding action of strong acids poured down the pipes. Radiator valves are turned out of adjustment, boilers are burned out, and hundreds of other things happen to this part of the house because of careless hands. Thus we may say that the important factors of depreciation which an architect should keep in mind are unequal settlement, action of frost, washing-out effects of rain-water, corrosion, the heat of the sun, the artificial heat of the furnace, and the foolishness of tenants. Unequal settlement can be prevented by carefully examining the construction, and the action of frost, heat, and sun can be minimized by the use of proper materials, and the foolishness of tenants can be partly offset by selecting those mechanical devices which are as near fool-proof as human hands can make them. XIII SELECTING MATERIALS FROM ADVERTISEMENTS