ORDINARY MEETING.* 



Professor E, Hull, F.R.S., in the Chair. 



The Minutes of the last Meeting were read and confirmed. The 

 following paper was then read : — 



THE HUMAN COLOUR SENSE, AND ITS AC- 

 CORDANCE WITH THAT OE SOUND, AS 

 BEARING ON THE ''ANALOGY OF SOUND 

 AND colour:' Bv Dr. John D. Macdonald, 

 I.H.R.N., F.R.S. 



IN dealing with the sense of colour it is usual for writers 

 to affirm that " colour is in fact an internal (subjective) 

 sensation," and has no external and objective existence, 

 but surely this can only be true in part. Now that we are 

 able to obtain colour as well as outline light and shade in 

 photography, objective conditions must be present in all. 

 The word subjective is only applicable where colour vibra- 

 tions are induced in the nerve terminals independently 

 of any corresponding objective vibrations impinging on the 

 retina, ^Ve are still confronted by the " ultimate fact " that 

 a certain wave length will induce in us the sensation of Red 

 and not Blue, and vice versa, while the intermediate wave 

 length will induce Yellow and nothing else. We may use 

 the Avord subjective in this connection, but it gives us no 

 further insight into the true cause of a specific colour sense. 



* Monday, 1st February, 1897. 



