210 NATUEAL HISTORY 



came to try it's 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 

 wood 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 expe- 

 riments, is the stone-built, tiled hop-kiln in Gally-Lane, which 

 measures in front 40 feet, and from the ground to the eaves 

 12 feet. The true centrum phonicum, or just distance, is one 

 particular spot in the King 's-fald, 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 

 meer 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 Oxford- 

 shire, allows 120 feet for the return of each syllable 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 75 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 ad- 

 mitted 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 



