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none of any transverse motion of the air ; for the particles 

 are raised by the current, and fall again by their gravity, 

 without exhibiting any symptoms of transverse motion; for 

 the motion of the air from the sides, to supply the place of 

 that driven away, must not be considered as transverse or 

 undulatory, for it is only a secondary current ; and, indeed, 

 its path, though curved, is not of an undulatory character. 

 And I think the nature of the vibrations of columns of air 

 (as in the organ pipe) gives some weight to the idea of direct 

 impulse ; for the pitch is dependant on the length of the pipe, 

 and is affected by the diameter of the pipe in a very slight 

 degree. But if the vibrations were of an undulatory nature, 

 that is, vibrating from side to side of the pipe, it would be 

 probable that by doubling the diameter of the pipe, or 

 increasing its internal capacity four times, the tone should be 

 two, or at least one octave lower. But doubling the diameter 

 of an organ pipe does not lower the pitch more than in- 

 creasing its length by about one-thirtieth part. 



It, therefore, appears most probable that the production 

 and transmission of sound is by direct impulses ; but I think 

 we ought to have a much greater weight of experimental 

 evidence before we allow that more than a primu facie case 

 is made out. 



The Rev. Dr. Scoresby conceived that the undulating 

 theory of light was so well established, that it was assuming 

 a bold position to attack it. The phenomena afforded by 

 the Solar Spectrum and by Newton's Rings were affirmatory 

 of the truth of this theory, and had been proved correct by 

 a series of long mathematical investigations. The polariza- 

 tion of light added a further proof towards the fact. 



After some discussion, Mr. W. S. Ward replied that he 

 thought that a theory of light assuming its materiality and 



