238 Proceedings of Royal Society of Edinburgh. [sess.. 
the ear through the resonant cavity, which must modify them 
immensely. An influence of this kind has been already noted in 
the case of x and x : but the influence of the fore-cavity of s and f 
is probably much stronger than that of the divergent tube of x and 
X- The effect of that influence will be to damp all the frictional 
noises which are either graver or more acute than the range of the 
resonance of the cavity ; whilst all noises within that range will 
be more or less exaggerated. 
In the phonogram of /, therefore, we ought perhaps to find the 
resonance subject to very strong distortions, but none of them 
either much longer or much shorter than the waves of the reso- 
nance itself. The same remark does not quite apply to s ; the 
original frictional noises are so much acuter and weaker as not to 
afford the groundwork for similar results. The frictional noises- 
are perhaps renewed at the teeth. In any case the ear seems to 
testify that they survive in an acuter form than those of f. Here,, 
as elsewhere, the appearance of good phonograms must be awaited.. 
Effects of Combination : Glides. 
It is necessary to say something here about the effects of com- 
bination with other phones upon the acoustic composition of the 
class of consonants just treated. Tor though the spirate fricatives, 
and, indeed, all fricative consonants, can be produced and studied 
in an isolated form, they are never found isolated in actual speech. 
The very name ‘ consonant ’ indicates that in ordinary language 
they are never sounded alone. There are some consonants which 
it is difficult, or even impossible, to sound alone. Such sounds are 
essentially connective and transitional. Unlike the fricatives, they 
never consist, and never can consist, of a succession of similar 
sounds : it is of their essence to change continuously ; in other 
words, they are not continuant, but gliding. But there are con- 
ditions of combination in actual speech, as will perhaps have been 
already gathered, which cause the fricatives themselves to glide 
through very considerable changes, even in the duration of a single 
utterance of any one of them. We cannot consider their possible 
combinations at this point exhaustively, because all other conso- 
nants remain yet to be explored ; but we can consider their com-.- 
