BULLETIN 



OF THE 



ESSEX I3SrSTITTJTE 



Vol. 11. Salem, July, Aug., Sept., 1879. Nos. 7, 8, 9. 



The Enharmonic Key-board of Prof . Henry Ward Poole, 



By Theodore M. Osborne. 



It has long been the great problem of musical theorists 

 to devise a keyed instrument which shall be capable of 

 modulations into different keys, and at the same time be 

 justly intoned for both major and minor intervals in each 

 key, without being too complicated for the actual perfor- 

 mance of ordinary music. The kej'board to be described 

 in this paper is oflered as one of the solutions of that 

 problem. Before entering upon the details of its con- 

 struction, it is necessary briefly to review the modern 

 physical theory of harmony. 



The principle of simf)le ratios, as it has been called, 

 which has proved to be the key of theoretical harmony, 

 was known in its application to the ancients, who deter- 

 mined the relative lengths of the parts of a stretched 

 string sounding the different tones of the scale. But the 

 explanation and the development of this principle could 

 not possibly be made before the discovery of the wave 



ESSEX INST. BULLETIN. XI 9 (109) 



