252 NATURAL HISTORY 
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 va- 
rious experiments, in the stone-built, tiled hopkiln 
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 cartway. In this case there is no 
choice of distance; but the path, by mere contin- 
gency, 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 one 
hundred and twenty feet for the return of each syl- 
lable distinctly ; hence this echo, which gives ten 
distinct syllables, ought to measure four hundred 
yards, or one hundred and twenty feet to each syl- 
lable; 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 
