that all beyond this given length
is nothingness, and gives out no sound. What shall we say then? that
doubling the length of the tube destroys the vibration of the imprisoned
air? Nay, verily, the air still vibrates, sound is still produced, but
_the note is below the gamut of the natural ear_, which was created to
comprehend only sounds within a certain compass: its capacity goes no
farther, and any sound pitched either above or below that compass we
cannot perceive. In proof of this is the simple fact that a cultivated
ear--that is, an ear of enlarged capacity, can readily catch the
faintest harmonics of a guitar, to which others are totally deaf.

Again: I have stood by the Falls of Niagara, and listened in vain for
that deep, unearthly roar of which so much has been written and sung.
The rush and the gurgle of the waters was there, the sweeping surge of
the mighty river, but Niagara's hollow roar was absent. Again and again
my ears were stretched to catch the awful sound, till the effort became
almost painful, but in vain. And yet the sound was present, ay!
eternally present, but the note was just beyond the gamut of my ear.
Standing thus for some moments, gazing and listening with the most
earnest attention, nature, through her hidden laws, wrought a miracle
in my person. The long-continued strain enlarged the capacity of the
ear, even as the muscles of the arm are strengthened by frequent and
energetic action, or as a faculty of the mind itself is developed by
exercise. Lower and lower sank the scale of my aural conceptions, till,
as it approached the keynote of the cataract, a low murmur began to
steal in upon me, deeper than the deepest thunder tones, and seemingly a
thousand miles distant. Louder and louder it swelled, nearer and nearer
it approached as the hearing faculty sank downward, till the keynote was
reached, and then--the rush and gurgle of the waters was swept away, and
in its place resounded the awful tones of earth's deepest _basso
profundo_. Then for the first time I realized the terrible sublimity of
Niagara--the voice of God speaking audibly through one of the mightiest
works of His creation.

And as, musing, I moved away from the appalling scene, the thought
rushed into my mind that perhaps my experience of a few moments might be
that of the soul when entering upon the sublimities of the future state.
Hence my theory, which may go for what it is worth, or, as the Yankees
would say, is 'good fo