SELBORNE, _Feb._ 12_th_, 1778.
"Forte puer, comitum seductus ab agmine fido,
Dixerat, ecquis adest? et, adest, responderat echo,
Hic stupet; utque aciem partes divisit in omnes;
Voce, veni, clamat magna. Vocat illa vocantem."
Dear Sir,--In a district so diversified as this, so full of hollow vales
and hanging woods, it is no wonder that echoes should abound. Many we
have discovered that return the cry of a pack of dogs, the notes of a
hunting-horn, a tunable ring of bells, or the melody of birds very
agreeably; but we were still at a loss for a polysyllabical articulate
echo, till a young gentleman, who had parted from his company in a summer
evening walk, and was calling after them, stumbled upon a very curious
one in a spot where it might least be expected. At first he was much
surprised, and could not be persuaded but that he was mocked by some boy;
but repeating his trials in several languages, and finding his respondent
to be a very adroit polyglot, he then discerned the deception.
This echo in an evening, before rural noises cease, would repeat ten
syllables most articulately and distinctly, especially if quick dactyls
were chosen. The last syllables of
"Tityre, tu patulae recubans . . . "
were as audibly and intelligibly returned as the first; and there is no
doubt, could trial have been made, but that at midnight, when the air is
very elastic, and a dead stillness prevails, one or two syllables more
might have been obtained; but the distance rendered so late an experiment
very inconvenient.
Quick dactyls, we observed, succeeded best; for when we came to try its
powers in slow, heavy, embarrassed spondees of the same number of
syllables,
"Monstrum horrendum, informe, ingens . . . "
we could perceive a return but of four or five.
All echoes have some one place to which they are returned stronger and
more distinct than to any other; and that is always the place that lies
at right angles with the object of repercussion, and is not too near, nor
too far off. Buildings, or naked rocks, re-echo much more articulately
than hanging woods or vales; because in the latter the voice is as it
were entangled, and embarrassed in the covert, and weakened in the
rebound.
The true object of this echo, as we found by various experiments, is the
stone-built, tiled hop-kiln in Gally Lane, which measures in front forty
feet, and from the ground to the eaves twelve feet. The true _centrum
phonicum_, or just distance, is one particular spot in the king's field,
in the path to Nore Hill, on the very brink of the steep balk above the
hollow cart-way. In this case there is no choice of distance; but the
path, by mere contingency, happens to be the lucky, the identical spot,
because the ground rises or falls so immediately, if the speaker either
retires or advances, that his mouth would at once be above or below the
object.
We measured this polysyllabical echo with great exactness, and found the
distance to fall very short of Dr. Plot's rule for distinct articulation;
for the doctor, in his history of Oxfordshire, allows a hundred and
twenty feet for the return of each syllable distinctly; hence this echo,
which gives ten distinct syllables, ought to measure four hundred yards,
or one hundred and twenty feet to each syllable; whereas our distance is
only two hundred and fifty-eight yards, or near seventy-five feet, to
each syllable. Thus our measure falls short of the doctor's, as five to
eight; but then it must be acknowledged that this candid philosopher was
convinced afterwards, that some latitude must be admitted of in the
distance of echoes according to time and place.
When experiments of this sort are making, it should always be remembered
that weather and the time of day have a vast influence on an echo; for a
dull, heavy, moist air deadens and clogs the sound; and hot sunshine
renders the air thin and weak, and deprives it of all its springiness,
and a ruffling wind quite defeats the whole. In a still, clear, dewy
evening the air is most elastic; and perhaps the later the hour the more
so.
Echo has always been so amusing to the imagination that the poets have
personified her; and in their hand she has been the occasion of many a
beautiful fiction. Nor need the gravest man be ashamed to appear taken
with such a phenomenon, since it may become the subject of philosophical
or mathematical inquiries.
One should have imagined that echoes, if not entertaining, must at least
have been harmless and inoffensive; yet, Virgil advances a strange
notion, that they are injurious to bees. After enumerating some probable
and reasonable annoyances, such as prudent owners would wish far removed
from their bee gardens, he adds--
. . . "aut ubi concava pulsu
Saxa sonant, vocisque offensa resultat imago."
This wild and fanciful assertion will hardly be admitted by the
philosophers of these days, especially as they all now seem agreed that
insects are not furnished with any organs of hearing at all. But if it
should be urged, that though they cannot hear yet perhaps they may feel
the repercussions of sounds, I grant it is possible they may. Yet that
these impressions are distasteful or hurtful, I deny, because bees, in
good summers, thrive well in my outlet, where the echoes are very strong;
for this village is another Anathoth, a place of responses and echoes.
Besides, it does not appear from experiment that bees are in any way
capable of being affected by sounds; for I have often tried my own with a
large speaking-trumpet held close to their hives, and with such an
exertion of voice as would have hailed a ship at the distance of a mile,
and still these insects pursued their various employments undisturbed,
and without showing the least sensibility or resentment.
Some time since its discovery this echo is become totally silent, though
the object, or hop-kiln, remains; nor is there any mystery in this
defect; for the field between is planted as a hop-garden, and the voice
of the speaker is totally absorbed and lost among the poles and entangled
foliage of the hops. And when the poles are removed in autumn the
disappointment is the same; because a tall quick-set hedge, nurtured up
for the purpose of shelter to the hop ground, entirely interrupts the
impulse and repercussion of the voice; so that till those obstructions
are removed no more of its garrulity can be expected.
Should any gentleman of fortune think an echo in his park or outlet a
pleasing incident, he might build one at little or no expense. For
whenever he had occasion for a new barn, stable, dog-kennel, or the like
structure, it would be only needful to erect this building on the gentle
declivity of a hill, with a like rising opposite to it, at a few hundred
yards distance; and perhaps success might be the easier ensured could
some canal, lake, or stream intervene. From a seat at the _centrum
phonicum_ he and his friends might amuse themselves sometimes of an
evening with the prattle of this loquacious nymph; of whose complacency
and decent reserve more may be said than can with truth of every
individual of her sex; since she is . . .
" . . . quae nec reticere loquenti,
Nec prior ipsa loqui didicit resonabilis echo."