PULSE AND RHYTHM. 429 



The foregoing examples, although following the pulse in their ex- 

 actness, are still for scientific purposes not quite what may be desired. 

 The heart's action varies. So do musical tempi. Both are disturbed 

 by the slightest exciting or nervous influences. Still the track, though 

 faint at times, sometimes quite effaced by conscious effort, is there; 

 corroborated through a hundred different channels. One distinguished 

 psychologist* finds that a subject could repeat simple intervals with- 

 out accent with greatest exactness when these intervals lay between 

 0.4 and 0.7 seconds. It takes but a simple problem in arithmetic to 

 see that this agrees with from 75 to 86 rhythmic beats per minute, or 

 the region of pulsation common to the human pulse. Another f on 

 conducting a series of experiments on rhythm, 'the first and most 

 important object of which was to determine what the mind did with a 

 series of simple auditory impressions in which there was absolutely 

 no change of intensity, pitch, quality or tone interval,' finds that the 

 pulse seemed at times to impose a grouping in which the clicks coming 

 nearest to the time of the heart beats were accented. 



To Professor BoltonJ must be given the credit of having success- 

 fully found the means by which rhythm can be permanently differ- 

 entiated from time in music. He says this general principle, arrived 

 at by the same experiments, may be stated: "The conception of a 

 rhythm demands a perfectly regular sequence of impressions within 

 the limits of one second and one hundredth of a second. When a 

 longer interval was introduced into the series, the impressions coming 

 between the long intervals fell together into a group but they did not 

 form an organic unity. There was no pleasure in such a rhythm. 

 Something seemed to be looked for in this longer interval which was 

 wanting. ' ' Why ? 



No matter how slowly one sound follows another, time, as under- 

 stood in music, can still be a characteristic of the sequence. A clock 

 may strike this minute and not again for an hour, but time is still 

 being measured. A rhythm, however, can be said to exist only when 

 sounds succeed each other so as to fall within the same limited horizon 

 of attention. This differentiation has not to this day been clearly 

 made by authors of musical encyclopedias and dictionaries, they having 

 been satisfied with considering rhythm as simply similar in music to 

 meter in verse. 



Bearing these statements in mind, it seems improbable that the 

 mere physical activities and industries of primitive peoples, such as 

 cradle-rocking, spinning and grinding should have been so constantly 

 of one rhythm as to impress accidentally a beat of such uniform 

 variation, extending within fifteen pulsations difference a minute 



* ' The Psychology of Rhythm,' Am. Journ. of Psychol., January, 1902. 

 t American Journ. Psychol., Vol. VI., No. 2. 

 t Ibid. 



