When explosives are used, as in b attlef i eld scenes, special- e ffe c ts men usually receive extra pay. There is danger, and sometimes there are accidents. For a large battlefield scene, the special effects man talks with the director, examines the area, and plans the e ffe c t several days before the filming is to begin. He then places his explosives. They must not be too powerful in the areas where actors will pass. But there must be enough power s o that with sound e ffects added later the explosions seem real. The special-effects man may cover two acres of ground with explosives, each connected individually by wire to a special device for controlling the course of an electric current. When the scene begins, he causes explosions in the air by sending up large bags f illed with explosives. The bags float in the air and are held by wires. A the right time he makes them explode. If a church tower, for example, must seem to be hit by guns, he puts explosives in several places in the tower. He usually cuts through some of the supports of the tower first so that he can be sure they will fall.