However , on November 5 , 1938 , he conducted the world premieres of two orchestral works by Samuel Barber , `` Adagio for Strings '' and `` Essay for Orchestra '' .
However , in 1938 , he conducted the world premieres of two orchestral works by Samuel Barber , `` Adagio for Strings '' and `` Essay for Orchestra ( Barber ) | Essay for Orchestra '' .