226 Proceedings of Royal Society of Edinburgh. [sess. 
length of the frictional passage is at most the thickness of the 
teeth, about 3 mm. But in 6 it is from 4 to 6 times this length : 
the resistance to the breath is much greater : and these conditions 
are essential ; for if the application of the tongue is relaxed in such 
a way that friction only takes place against the tip, and not also 
against the blade of the tongue, the sound becomes much more like 
/ than 6. Whether this difference in the exciting noise leads also 
to any marked difference in the resonance excited, it would he 
premature to say. The ear testifies that in passing from / to 0, the 
slight rise in pitch is accompanied by a great increase in shrillness 
of quality. This may he due only to the new friction. But the 
narrowing of the tube has made it more capable of producing an 
overtone. Some trace of the first overtone might reasonably he 
looked for. 
Here the matter must rest until the phonographic traces of / 
and 6 have been sufficiently magnified and accurately compared. 
The successes of Dr Boeke and M. Ma,richelle in obtaining magni- 
fied photographs of phonographic tracings justify great hopes of 
successful comparison. But such a comparison will he very diffi- 
cult to follow out, unless care is taken that the resonance is at the 
same pitch in both examples. This might he secured pretty nearly 
by recording them in connection with an identical vowel. But 
there are pitfalls in all pronunciations of connected sounds, which 
will he noted by and by ; if they could he recorded at the same 
pitch in isolation, it would he much better. The frictional noises 
will doubtless come out in the phonogram as distortions of the 
resonance. These ought to he much longer and deeper in 6 than 
in f; and if there is an overtone, it ought to show itself in a 
tendency of the resonantal vibrations to flatten or notch themselves 
in the middle. 
x and x- 
These are the sounds of ch in the Scotch words licht and loch. 
They are heard also in German words like icli and doch. They are 
very much alike in sound, and are best examined together; for 
they differ little in analysis, except in the actual pitch of resonance. 
But German phoneticians agree in representing them by two 
different signs, and there is in practice a certain physiological gap 
between them, which will he explained later. As in / and 0 , the 
