242 NATURAL HISTORY 



midnight, when the air is very elastic, and a dead stillness 

 prevails, one or two syllables more might have been ob- 

 tained; 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. Build- 

 ings 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 ex- 

 periments, is the stone-built, tiled hop-kiln in Gaily Lane, 

 which measures in front forty feet, and from the ground to 

 the eaves twelve feet. The true centrum plionicum, 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 dis- 

 tance ; 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 exact- 

 ness, 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 120 feet for the return of each syl- 

 lable distinctly ; hence this echo, which gives ten distinct 

 syllables, ought to measure 400 yards, or 120 feet to each 

 syllable ; whereas our distance is only 258 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 



