108 SCIENCE PROGRESS 



of 256 vibrations per second (about the pitch of middle C in the 

 piano) about one second is required before resonance of the 

 other fork becomes audible, that is, 256 air waves have to 

 impinge on this resonating fork before its resonance accumu- 

 lates sufficiently to become audible. 



With a pair of forks making 1920 vibrations per second 

 (about three octaves higher than in the first experiment) he 

 found that he was unable to damp the first fork sufficiently 

 soon after striking it before the resonance was audible in the 

 second fork. 



If the basilar membrane is a series of resonators it is clear 

 that the lower pitched tones will, according to Mr. Sedley 

 Taylor's experiment, take longer to receive audible resonance 

 than the higher tones. How is it possible, under these condi- 

 tions, to imagine that rapid arpeggio musical passages could 

 be distinctly heard if so much more time were required for the 

 lower notes to resonate than the higher ? 



These considerations have driven us to the conclusion 

 that a dead beat transference of pressure and motion is the 

 only solution which can satisfy this problem, and that we have 

 to look for a series of actual impulses to be set up in the cochlea 

 as the varied wave pressures produced in the liquid are con- 

 veyed through the corti arches direct to the hairlets. 



These periodic impulses in many series are shown to exist 

 in the compound wave-forms in the liquid, their maxima of 

 pressure, whether positive or negative, with the crossing points 

 at the axis of the pressure curve, furnish evidence of not only 

 the periodic impulses of the original tones, but of the Differ- 

 ential and Summational Tones, Octaves and Harmonics. 



Yours faithfully, 



Thomas Wrightson. 



II 



THE ICE-AGE QUESTION 



From H. Spencer Jones, B.Sc 



Dear Sir, — In the last issue of Science Progress appeared 

 an article entitled " The Ice-Age Question Solved," by Major 

 R. A. Marriott, D.S.O. In his article, certain conclusions of 

 a geological nature were held to be in accordance with and 



