High officials of the Army Engineer Corps who have studied various ways of confusing enemy bombers at night say that blackout of all illumination visible from the air will continue to be favored for protection of cities and industries. They express doubt concerning the effectiveness of fixed lighting patterns or dim-outs. The United States, with its long coastline and vast interior, presents defense problems exactly opposite to those of Great Britain. An enemy flyer can reach any city by instruments, and at comparatively low altitude can pick up features of the terrain, rivers, hills, etc., to guide him to the target spotted on his map. If a pattern of lights confronts him on the ground, he would not attempt to find his chosen target by these lights, but once he spots it by features of the terrain shown on his map, he could use the lights as reference points to guide him while maneuvering to get over the target. Inother words, lights supposed to confuse any attacker may actually aid him, and therefore dim-outs as well as light patterns are looked upon as less effective than total blackouts. If a blackout is complete, the pilot may be able to find his target by noting the terrain, but the instant he begins to circle or maneuver he probably would lose it again if there were no lights to serve as reference points.