WASHINGTON-John L. Lewis, head of the United Mine Workers of America, tonight called district union representatives to meet here tomorrow to answer a fourth demand from President Roosevelt that 53,000 captive coal miners end their strike immediately.

The call went out after the President personally had taken a hand in efforts to mediate the dispute at a White House conference with Lewis, Myron C. Taylor, a director of U.S. Steel one of the largest owners of captive mines, and William H. Davis, chairman of the National Defense Mediation Board.

The meeting lasted nearly two hours. The trio had spent four hours in conference at the Mayflower Hotel before carrying their discussions to the White House.

Mr. Roosevelt asked Lewis and Taylor in reopen the mines immediately on the understanding that the Defense Mediation Board would consider the miners' demands chief of which is insistences on the union shop when it meets on Friday and continuously thereafter.

Lewis would not give a final answer tonight. He said one would be forth coming tomorrow after he meets with his district leaders.

KUIBYSDEV, Russia--German artillery has unleashed the greatest barrage of the war against the Moscow approaches and the city's defenders expected an onslaught, but without waiting for it they have started an waiting for it they have started an offensive which has driven the Germans from six towns, war dispatches said today