732 



'.CIENCE. 



[N. S. Vol. XI. No. 280. 



more grades of product may be shown by 

 different shadings or the relative amount of 

 healthy and diseased fruit or vegetable. 

 Like all similar devices, they admit of er- 

 rors of statement and need to be constructed 

 with great care and then should always 

 form an adjunct of the text. 



The personal equation needs to be re- 

 duced to the lowest terms and the experi- 

 menter should test this at frequent inter- 

 vals by calling to his aid the judgment of 

 the disinterested person, who is competent 

 to arbitrate. A person with his eye fixed 

 upon some point to be reached may be ob- 

 livious to side lights that play an important 

 part. 



The born experimenter we may expect in 

 the next generation, but the present station 

 workers needed to be made and that quite 

 quickly. When the ideal ti-uth searcher 

 comes we shall be shown how best to work 

 for the truth, the whole truth, and nothing 

 but the truth. 



Btron D. Halsted. 



CoLLEGB Experiment Station, 

 New Bktjnswick, N.J. 



MODERN PROBLEMS IN ACOUSTICS* 



The subject of acoustics appeals in one or 

 more of its phases to a wide range of people : 



To the mathematician, for the laws of 

 vibrating bodies furnish countless problems 

 that tax his science to the uttermost ; 



To the physicist, to whom primarily the 

 field belongs ; 



To the architect, whose business it is to 

 design auditoriums fitted for hearers as 

 well as for spectators ; 



To the anatomist and physiologist, who 

 finds in the organ of hearing a wonderfully 

 complex structure that is incomprehensible 

 without the aid of acoustical principles ; 



To the psychologist, who investigates the 



* A Eeport from the Committee on Physical Science 

 presented to the Washington Philosophical Society by 

 Charles K. Wead. 



operations of the mind concerned in the 

 hearing of sound ; 



To the instrument-maker, who must fur- 

 nish the musician the means of expression 

 and help him develop them ; 



To the musician, who cares to know the 

 historical development and the foundations 

 of his present art ; 



To the ethnologist, who recognizes music 

 as one of the most important expressions of 

 the life of a people ; and lastly. 



To all intelligent men who find with the 

 Roman ' nothing of human interest alien to 

 them,' and realize that a subject of such 

 world-wide, time-long, interest as music 

 may be studied profitably even by those 

 who are not numbered among musical per- 

 formers. For they appreciate the fact that 

 here, as everywhere, the ability to learn 

 ivhy the alien does what he does, to enter 

 sympathetically into his thought and see 

 through his eyes, is the subtle power which 

 distinguishes culture from mere knowledge. 



In accordance with the custom of these 

 Reports we are to take a bird's-eye view of 

 recent progress in the science of acoustics. 



I. In the history of acoustics two names 

 are pre-eminent : Chladni, the text-book 

 writer, who united to wide knowledge of 

 the subject great ingenuity and experimen- 

 tal skill ; and Helmholtz in whom there 

 was a unique combination of mathemati- 

 cian, physiologist, physical experimenter 

 and musician. His Seiisations of Tone as a 

 Physical Basi^ for Music published (in Ger- 

 man) in 1863, and his monographs sum- 

 med up in it, contained enough in each 

 of these four lines to make one famous. 

 The book has for nearly forty years domi- 

 nated the thoughts of most people who 

 believe that the science of acoustics has 

 anything to teach musicians. Still it is 

 significant that musicians have largely re- 

 fused to recognize its sway, some showing 

 crass ignorance in their comments, others 

 making it clear that there is something in 



