Proceedings of the American Academy of Arts and Sciences. 

 Vol. XLII. No. 7. — July, 1906. 



CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 



HARVARD COLLEGE. 



ON THE CONDITIONS TO BE SATISFIED IF THE 

 SUMS OF THE CORRESPONDING MEMBERS OF 

 TWO PAIRS OF ORTHOGONAL FUNCTIONS OF 

 TWO VARIABLES ARE TO BE THEMSELVES 

 ORTHOGONAL. 



By B. Osgood Peikce. 



