Adhesive tape applied in strips to windows in localities subjected to aerial bombing is helpful in protecting the glass against shattering. Experiments made at the British Ministry of Home Security Research Laboratories, to determine in which designs the tap is most effective, required the building of a tunnel-like structure in which four specimen windows are installed. These are treated in various forms with adhesive, and then a large balloon charged with explosive gases is fired electrically, throwing a blast wave into the tunnel. The effect of the blast approximates that of a 500-pound bomb striking about 80 feet from the window.