Furthermore, as _Specula's_ may be so order'd, that by Reflection they shall make one single thing appear many different things; as one single Man to seem many Men, differing as to Shape and Complexion (or a company of Men) which I think Sir _Samuel Moreland_'s Contrivance does not: So may _Ecchoing Bodies_ also be order'd, that from any one Sound given, they shall produce many Ecchoes, different both as to their _Tone_ and _Intension_. (The ground whereof has elsewhere been laid down in a Treatise concerning the _Sympathy of Lute-strings_.) By this means a _Musical Room_ may be so contriv'd, that not only one Instrument, play'd on in it shall seem many of the same _sort_ and _size_; but even a Consort of (somewhat) different ones; only by placing certain _Ecchoing Bodies_ so, as that any Note (play'd) shall be return'd by them in 3_ds_, 5_ths_, and 8_ths_, which is possible to be done otherwise than was mention'd before in _Refracted Audition_. I have now done with my _Comparison_ of the two Noblest _Senses_, and _Sciences_, as to their _Improvements_; wherein I have been thus large, that I might give you a little prospect into the _Excellency_ and _Usefulness_ of _Acousticks_; and that thereby I might excite all that hear me, to bend their Thoughts towards the making of Experiments for the compleating this (yet very imperfect, tho' noble) Science; a _Specimen_ whereof I will give you in three _Problems_, and then present you with the _Semiplane_ of an _Acoustick or Phonical Sphere_, as an Attempt to explicate the great _Principle_ in this Science, which is _The Progression of Sounds_. _The Problems are these:_ 1. _Sonum intendere quousque velis_; or, _Datum sonum ad datum gradum intendere_. 2. _Sonum extendere quousque velis_; or, _Datum sonum ad datum distantiam extendere seu propagare_. 3. _Sonum transire ab extremo ad extremum_ & _non per Medium_. 1. The first is, _To make the least Sound_ (by the help of Instruments) _as loud as the greatest_; a whisper to become as loud as the shot of a Cannon. By the help of this _Problem_, the most minute Sounds in Nature may be clearly and distinctly heard. 2. The second is, _To propagate any_ (the least) _Sound to the greatest distance_. By the help hereof any Sound may be convey'd to any, and therefore heard at any distance, (I must add, within a certain, tho' very large Sphere.)