LECTURE  V

I. Quality of Sensation ; General Remarks upon the Sensa¬
tions OF Pressure, Temperature, Taste, and Smell. § II. Tone-
sensations; Beats. § III. Clang-colour; Simultaneous Clangs.
§ IV. Noises. § V. Measurement of Differences of Tone-
sensations ; The Tonal Scale ; Relations to Weber's Law.
 

THE intensity of a sensation is only one side of it. Not
only has every sensation its own intensity, but also a
definite quality which renders it distinguishable from other
sensations.

The most extreme instances of qualitative difference are
furnished by the sensations of the different sense-organs,—sensa¬
tions of eye, ear, and skin. A colour and a tone, a sensation
of pressure and one of warmth, are simply incomparable with
each other. Hence they are denominated disparate sensations.
But qualitative differences are also to be observed within the
sphere of one and the same sense. Thus red, green, blue, and
yellow are entirely different sensations, although they are all
sensations of sight. The one thing that proves a closer inter¬
connection among these sensations of a single modality is the
possibility of a continuous passage between any two of them,
the one passing by stow degrees into the other. Thus red may
pass into green, or a low into a high tone. So that the
relation between two different sensations within one sense is
analogous to that between two points which lie within one and
the same spatial continuum ; while two disparate sensations
may be compared to points which belong in entirely different
spaces, and whose position with regard to each other is un¬
known.

There is no sense-organ within whose sphere qualitative
differences do not occur in greater or less number.    Sometimes

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