14° MifcellaneaCuriofa* 



lots in mighty tempeftuous Weather, when Ugh* 

 Houfes are render'd almoft ulelefs \ but alio for the 

 meafuring the ftrength of Winds, if allowance 

 be made for their different moifture. For 1 

 conceive, that the more dry any Wind is, the 

 louder it will whittle ceteris paribus ; I fay, ce- 

 teris paribus, becaufe, befidef the ftrength and 

 drynefs of Winds or Brea|f[ there are a great 

 many other things (hereafter to be confidered) 

 that concur to the increafe or magnifying 

 of Sounds, begotten by them in an Inftru- 

 ment expofed to their Violence, or blown in- 

 to. 



3. The third Problem, is, That a Sound may 

 he conveyed from one extreme to the other (or from 

 one diftant place to another,) fo as not to be heard 

 in the middle* 



By the help of this Problem a Man may talk 

 to his Friend at a very confiderable diftance, fo 

 that thofe in the middle fpace mail hear nothing 

 of what paffed betwixt them. 



FIG. V. TAB. III. 



Semiplanum Sfhara Phomca feu Acouflha. 



You are to conceive that (rude) Semiplane, 

 as parallel to the Horizon .- For if it be per- 

 pendicular thereunto, I fuppofe the upper ex- 

 tremity will be no longer Circular, but Hyperbo- 

 lical, and the lower part of it fuited to a grea- 

 ter Circle of the Earth. So that the whole 

 Phonical Sphere (if I may fo call it) will 

 be a lblid Hyperbola, (landing upon . a C<m- 

 cave Spherical Bafe. I fpeak this concern* 

 ing Sounds made (as ufually they oxe) nigh* the 



Earth, 



