 After leaving the army in January 1919 , Grainger refused an offer to become conductor of the Saint Louis Symphony Orchestra and resumed his career as a concert pianist . He was soon performing around 120 concerts a year , generally to great critical acclaim , and in April 1921 reached a wider audience by performing in a cinema , New York 's Capitol Theatre . Grainger commented that the huge audiences at these cinema concerts often showed greater appreciation for his playing than those at established concert venues such as Carnegie Hall and the Aeolian . In the summer of 1919 he led a course in piano technique at Chicago Musical College , the first of many such educational duties he would undertake in later years . 
