Of 0XF0%T>~SH1%E. 13 



rather than others ; juft as in two Viols tuned to aVnifon, where 

 the firings being fcrewed to the fame tenfion, and their pores 

 t put into the fame figure, if you ftrike one, the correfponding 

 fixing of the other Viol prefently anfwers it : becaufe the firft 

 ftring being of fuch a tenfion, and having pores of fueh a form, 

 makes vibrations in the Air, fuitable only to the pores made by 

 the fame tenfion in the other ftring. 



25. As for Tautological Poljiphonou* Echo's, fuch as return a 

 word or more, often repeated from divers objects by fimple re- 

 flection, there are none here eminent ; the beft I have met with 

 is at Ewelme, on the fide of a bank, inaMeddow fouth and by 

 weft (about a furlong) from the Church : it returns the fame word 

 three times, from three feveral objects of divers diftances, which 

 I guefs may be, 1. The Manor, 2. The Church and Hoftital, 

 And 3 d . Colonel Martins houfe. Another there is near Oxford, a- 

 bout the eaft-end of Chrift Church new walk, that repeats three or 

 four fyllables twice over ; and a treble one at the moft northern 

 point of the Fortifications in New Parks j But there being many 

 better than thefe of the kind no doubt in other places, I fhall re- 

 fer ve their confideration at large to a better opportunity, and on- 

 ly take notice here by the way, that thefe are never of many Syl- 

 lables ; and that always, by how many more they are' of, by fo 

 many the fewer times they repeat them, becaufe fo great diftance 

 will be required for their objects, that they muft quickly be re;, 

 moved put of the reflex action of the voice : for fuppofe but z 

 fentence of ten fyllables, viz^. Gemitu nemita omne remugit, and 

 allow, as before, for the return of each fyllable 1 20 feet, the firft 

 object muft be 1200 feet off; and the fecond, with abatement for 

 diftance, at leaft 2000 ; and the third, certainly out of the 

 voices reach, beyond all hopes of any refponfe. Indeed, could 

 we meet with one of Mcrfennus's Echo's, where fixty nine feet 

 would return us a fyllable, then fuch an Hemijiick. might be re- 

 founded three times, or perhaps a whole Hexameter twice < yet 

 however fmall a fpace maybe found for the clear repetition of 

 fuch a Verfe, I cannot think it can poflibly be, that any Ecbb 

 fhould repeat one eight times over : for fuppofe a fmaller diftance 

 would fuffice, then that allowed by Merfennws, as but 350 yards 

 to a Verfe of feventeen fyllables, and allowing fome decreafe 

 for the objects diftances ; yet I do not doubt p but. two or 



three 



