766 PROFESSOR FLEEMING JENKIN AND J. A. EWING ON THE 
a single partial tone. Above a this partial is usually the prime ; below @ it is 
usually the octave of the prime. 
(2.) In the lower or duplex form of @ the amplitude of the second partial 
is sometimes as much as nine times as great as that at the prime, but in pitches 
below a the sound will still be recognised as @, even when the second partial 
is only from three to four times as large as the prime. The ratio of prime to 
second partial in this part of the scale is always much less for @ than it was 
for 6. 
(3.) For pitches below d the experiments do not warrant very positive con- 
clusions. The prominence of a single partial is less marked in this part of the 
scale, and at the same time the quality of the spoken vowel is exceedingly 
vague. 
(4.) There does not appear to be any one pitch having the marked character- 
istics for 7 which were possessed by the pitch 6° for 6. 
(5.) There is a critical pitch in the neighbourhood of @ or 06> at which a 
sudden change takes place in the form and composition of the waves produced 
by certain voices when speaking or singing @: at this point the pitch of the 
single prominent tone changes by a whole octave. 
This change is not made on account of any requirement of the ear, but 
probably on account of the difficulty in adjusting the mouth-cavity so as to 
continue the simple form on the lower notes. This conclusion follows from 
the facts mentioned above, that some voices would on different occasions give 
sometimes the simple and sometimes the duplex forms on @ and b> when sing- 
ing what was at least generically the same vowel sound, and that another voice, 
also pronouncing the same vowel, gave the simple form as low as the note # 
The prominent tone in @ is generally found within the region Db? to b. 
What may be termed the average pitch of the constituents of @ is on notes 
near d and @, lower than that of the constituents of 6, owing to the absence 
of the third partial, but the average pitch for @ is higher than for 6 on the 
notes f and g, and even on b? with voice 1: this arises from the comparative 
smallness of the prime. When the simple form is reached the average pitch 
of the constituents of @ is much lower than that of the constituents of 6. 
If, instead of considering the average pitch, we look at the pitch of the 
-highest prominent constituent, we find that this pitch is the same for @ and 
6 when sung on g by voices 1 and 5, and also when sung on a and b> by 
voice 1. Before proceeding to consider these and the foregoing facts with 
reference to the theory of vowel sounds, we shall complete the account of our 
experiments. 
A few observations were made of the curves given by the vowels a° (as im 
the word “ awe”) and @ (as in “father”). These vowels were fairly well spoken 
by the phonograph, though not quite so wellas z or 6. Fig. 9, Plate XX XIX., 
