30 The Relativity of Knowledge. 



We have been taught at school and college to look upon 

 sound and coloj.', odor and taste, as resultants of motion 

 and sensation. The phonograph and telephone are daily 

 demonstrating that sounds of all kinds are merely vibra- 

 tions borne to our senses by means of the ear. The speed 

 and method of vibrating of the disk form all the vocal 

 sounds in complete fidelity. A slow vibration gives a low 

 pitch, and a rapid one a high pitch. All the colors of 

 flowers, ribbons and rainbow are borrowed reflections from 

 the white light of the sun. Monochromatic light would 

 give a ghastly world. (Here the lecturer illustrated by il- 

 luminating with monochromatic light.) Light vibrations give 

 us the sensation of color. The slowest moving waves give 

 us red and the most rapid violet. Taste and odor are due 

 to contact-vibration rather than to that of waves, but are 

 subject to somewhat similar laAvs. Every sense has an 

 exceedingly narrow range. Less than a certain number of 

 atmospheric beats per second will give us no sound. More 

 than a certain number will likewise leave us in silence. 

 Ears are not all alike in this, some being able to hear a 

 higher pitch and others a lower one than their neighbors. 

 The sounds our ears can hear are within a finite range ; 

 those possible to Nature spread off into the inflnite both 

 above and below our powers. Colors are subject to the 

 same law. What the eye can see downward is limited by 

 the speed producing red, while vibrations of ether slower 

 and slower down to inflnity probably exist. What it sees up- 

 ward is a somewhat greater but still limited speed giving 

 violet, while waves of greater and greater speed running 

 upward inflnitely are embraced in Nature's compass. Make 

 proper telephonic connection from the sounding-board of a 

 piano to a remote room ; connect an octave of tuning-forks, 

 pro})erly arranged for damping ; play any tune on the piano 

 within the range of the forks, and they will reproduce it. 

 (The lecturer illustrated by striking a tuning-fork, which 

 conveyed its note to a second fork on a sounding-board, 

 which continued to vibrate after the one originally struck 

 was damped.) Strike notes higher or lower than your forks 

 and they will remain practically silent. A harp with the 

 range of a single octave will do the same. Duplicate every 

 note of the piano with a corresponding one in a tuning- 

 fork, and a reproduction of every piece played on the 

 piano, whether high or low, becomes possible. We are 



