ON TEMPERAMENT. 167 



facility and simplicity to have only twelve keys in the 

 octave ; it would be of great advantage if this facility could 

 possibly be retained. 



How then shall we go on instramentally to improve 

 matters? For the first method, I have here a form 1 of 

 Helmholtz's harmonium which is really very little complicated. 

 Any person understanding music can very soon master it. 

 There are two keyboards put into the place of one, the lower 

 of which is a comma sharper than the upper ; consequently, 

 when you want to lower any note a comma you can do it by 

 putting your finger on the upper keyboard, instead of the 

 lower one. This gets over a great many difficulties, but it is 

 not absolutely true. However, the great fault of equal 

 temperament is the third. If we have the third, sixth, 

 and the seventh approximately true, we have got over the 

 most important errors. Those intervals are to a great 

 extent accurate on this instrument ; the dissonance of the 

 sharp third itself is not, I think, beyond the limits of audi- 

 bility. Those who say so cannot possess very good ears. I 

 will give you the common chord, first on the single keyboard, 

 and then change to the third, a comma flattened, so that you 

 may hear the difference. Now I will take the sixth. When 

 you have heard the true interval you will see that the other is 

 decidedly out of tune, although it might pass muster if you 

 did not hear the correct interval. The first mode then is 

 Helmholtz's double keyboard with 24 notes. 



Then there is another contrivance equally simple in the 

 keyboard ; this is Mr. Ellis's harmonium. He accomplishes 

 his object by shifting the sound not by means of separate notes 

 or keyboards, but by combination stops. I wish I had the 

 instrument here to show you ; though if it had been here you 

 would have seen nothing. It is just like a common harmo- 

 nium, except that it has a few draw-stops which fulfil different 

 functions from those in the ordinary arrangement. 



The next is an instrument which you have probably all 

 seen in the Exhibition that of General Perronet Thompson. 

 Perronet Thompson adopted the system of increasing the 

 digitals up to the full number of sounds, though he did not 

 carry it out quite to the bitter end ; and therefore he does not 

 profess that his enharmonic organ plays in all the keys ; but 

 even he has about 72 keys to each octave, and he starts on the 

 1 Mons. Gueroult's, made by Debain. 



