160 LECTURES TO SCIENCE TEACHERS. 



to speak of presently, a schisma ; and I am going to ask a 

 friend of mine who has a fine tenor voice to sing a true in- 

 terval, and then we will compare it with the tempered interval, 

 as given by the common harmonium. 



Here is Selmholtz's harmonium, on which I can show you 

 very clearly what is a comma it seems to me very audible, 

 and perhaps Mr. Colin Brown will kindly play us a comma 

 on his instrument, and a schisma also. The schisma is only 

 Y^th of a comma, but I think you will agree with me it 

 can be distinctly heard. Now if my friend Mr. Jones will 

 sing a perfect 5th we will have the note sounded on the har- 

 monium, and I think you will notice the difference distinctly. 

 I admit the experiment is difficult, indeed only last night I 

 heard it denied by a great authority that it could be shown. 

 (A true fifth above tenor G was sung, and the D of the tempered 

 harmonium was shown to be distinctly flat to it.) Now the 

 question occurs, what is the best mode of getting over, of 

 covering up, or in some way retrieving these inherent errors 

 of the scale ? Ever since the early times of harmonic music 

 different plans have been suggested, some of them of con- 

 siderable historical interest. The principal was what is termed 

 the unequal temperament. It was used for organs in former 

 times, and is now termed mean tone, or meso-tonic. English 

 cathedral organs up to a recent period were tuned by this 

 system, and traces of it can be found in the music written for 

 them. Until lately I could have pointed out many organs, 

 and I believe there are some still, tuned on this system. The 

 organ of Canterbury Cathedral, with which I am somewhat 

 connected, has only lately been shifted from the old unequal 

 temperament, and the large organ in the Moorfields Roman 

 Catholic Chapel was only a few years ago tuned on the 

 unequal temperament. If you look carefully at the music of 

 the time, PurcelTs anthems, for instance, in Boyce's Cathedral 

 music, you will be able to notice th,at he palpably shirks 

 certain notes ; he avoids GJ for instance, because he knew 

 Gjf to be a treacherous note on this old temperament. When 

 the organ was altered at Canterbury a few years ago, some 

 pipes had to be cut, and others had to be lengthened ; the 

 lengthening was very considerable, the larger pipes had to have 

 no less than two feet of metal stuck on to them, so as to bring 

 them into tune. What was this unequal temperament then 1 

 It was an attempt at getting the more common scales accu- 



