SCIENTIFIC STUDY OF HUMAN TESTIMONY. 173 



it. Now this is the point: The proper way may be either (1) that a 

 particular vibration should fall upon it, or (2) that it should be set to 

 work to generate that vibration in itself. If the piano-wire only gives 

 the same sound when struck either hard or soft, it is because it is manu- 

 factured to do one particular kind of work, and it can do no other. 



Now we may pass from a piano-wire to a tuning-fork. We find 

 that, by using different quantities or different shapes of metal, these 

 instruments give out different notes. If all be of the same metal, the 

 different quantities of metal will give us a difference in the pitch. This 

 demonstrates that the pitch of a note is independent of any particular 

 quality of the substance set into vibration. Now, although a great 

 many musical instruments can sound the same note, yet the music, the 

 tone, which one gets out of them is very different. That is, the pitch 

 being the same, the quality of the note changes because the wave, or 

 rather the system of waves, which we obtain is different. For instance, 

 if we sound a note upon the violin, or the French horn, or the flute, or 

 the clarionet, anybody who knows anything of music will tell which is 

 in question, so that here we have in addition to wave-length and wave- 

 amplitude another attribute, namely, that which in French is called 

 " timbre," in German " Klangfarbe," and in English, " tone " or " qual- 

 ity." 



THE SCIENTIFIC STUDY OF HUMAN TESTIMONY. 



By GEORGE M. BEARD, M. D. 

 II. 



LIMITATIONS of the Senses. The senses, which have hitherto 

 been regarded as infallible, are even more narrowly defined than 

 the memory or the higher qualities of intellect. So narrow is the range 

 of vision and the sight is certainly the best of the five senses that the 

 retina can appreciate a few only of the rays that come from the sun. 

 The vibrations of ether beyond the red at one end of the spectrum, and 

 the violet at the other are of no value in vision, ethereal undulations 

 higher than seven hundred and ninety trillions a second, or lower than 

 four hundred trillions a second, being powerless to affect it. 



Equally striking is the limitation of vision as regards distance and 

 magnitude. Only under the most favorable conditions are heavenly 

 bodies of the sixth and seventh magnitude visible to the naked eye. 

 The extreme limit for small objects, according to the experiments of 

 authorities, is represented by a disk -g-fg- of an inch in breadth. The 

 aid afforded to the sight by the telescope and microscope is important, 

 and, in scientific research, indispensable ; but, as compared with the 

 infinitely great and the infinitely little in Nature, it is trifling. 



