189-£.] NEW YORK ACADEMY OF SCIENCES. 47 
generals are thus honored, scientists, artists and writers are 
passed by. 
Meeting adjourned. BaAsHrorD DEAN, 
Recording Secretary of Biological Section. 
J. F. Kemp, 
Recording Secretary. 
October 29th, 1894. 
The Academy met and listened to the first public lecture of 
the course for 1894-95, by Prof. J. F. Kemp, on the Mesabi 
Iron Range of Minnesota, illustrated by specimens and lantern 
views. J. F. Kemp, 
Recording Secretary: 
November 5th, 1894. 
ReGutarR Business MEETING. 
The Academy was called to order by President Rees, but as 
no quorum for the transaction of business was present the busi- 
ness meeting was adjourned one week. 
The section of Astronomy and Physics then organized, 
President Rees continuing in the chair, eight persons present. 
The minutes of the previous meeting were read and approved. 
The paper of the evening was then read by Prof. A. M. 
Mayer, “On the production of beats and beat-tones by two 
vibrating bodies, whose frequencies of vibration are so great as 
to surpass the limit of audibility.” 3 
Prof. Mayer outlined the discussion as to whether such inter- 
ference tones were subjective or objective, maintaining that they 
have an actual physical existence. In the attempt to prove the 
objective existence of these tones it was desired to produce 
