From Purpose and scope of Investigations: "The combustion investigations of bureau are carried on in two parts. One part is the study of the process of combustion in the fuel bed as affected by the rate of supplying air through the fuel bed, by the character of the fuel as regards structure and composition, by the thickness of fuel bed, by the method of feeding the coal and the air and by the method of heating the coal. The second part of the investigation is the study of the process of combustion of the gases and other combustible rising from the fuel bed in the combustion space, after a sufficient quantity of air has been added. The results of the study are given in this report."