To-day the weather strip is gentler and not only keeps the cold air at bay, but keeps out the dust and noise and permits the window to go up and down more easily because it runs on a metal track; really the weather strip allows it to glide like magic. To move a window with the weather stripping affixed is a pleasure which the weakest reed can enjoy. The dictionary says “the weather strip is a narrow strip, as wood edged with rubber prepared to be placed over crevices, as at doors and windows to exclude wind, rain, etc.” This is the old weather strip. To-day they are in general metallic tubular strips fitting into complementary depressions in metal linings or window sashes that are designed and shaped to seal the cracks that naturally occur between and around doors and windows and their frames, sealing up these openings so that the elements are turned back before they get even their noses into the house. They are made of non-corroding, non-rustable metals such as zinc, bronze and copper, and they keep their elasticity plus non-leakage qualities as long as, and sometimes longer than, the building itself. Every type of door and every type of window present different problems, and every window or door of each type has again different problems, so to each there must be different applications. The following will explain more particularly than the foregoing. THE SLIDING WINDOW The sliding window is the most general type to be treated. Here the top and bottom, sides and meeting rail must be considered. How to stop leakage and seal against unwelcome callers are the problems. At the top of the window, as in the illustration, two strips are used; the tubular protuberance in the head of the frame nestles cosily in the depressed concavity of the window sash. Some brands line the depression with metal--others do not. When the window is closed, there is a complementary interlocking device at the rail where the upper and lower sash meet, often in the upper sash of S shaped bronze and in the lower sash a hook-shaped copper strip. The side of the frame upon which the window is raised and lowered is a real problem. The weather stripping makes the window weather-proof, yet it makes it open and shut easier than it could before the application of the strip. [Illustration: _Courtesy of Monarch Metal Weatherstrip Co._ DOUBLE HUNG OR ORDINARY SLIDING WINDOW TREATMENT WITH WEATHERSTRIPS OBVIATES DRAUGHTS, DUST AND NOISE--SAVES COAL!]