be discuss'd, when the Nature, and Motion, or Progression of Sounds are well stated.
For the Improvement of Refracted Vision artificial Instruments have been made, by grinding or blowing Glasses, into a certain Figure, and placing them at due distances, whereby the Object may be (as 'twere) enabled to send forth its Rays more vigorously, and the Visive Faculty impower'd the better to receive them. And thus also Instruments may be contriv'd for the assisting both the Sonorous Body, to send forth its Sound more strongly, and the Acoustick Faculty, to receive and discern it more easily and clearly. For,
- As a fine Glass Bubble, fill'd with clear Water, and placed before a burning Candle or Lamp, does help it to dart forth its Rays to a
prodigious Length and Brightness: So an Instrument may be invented, that apply'd to the Mouth (or any Sonorous Body) shall send forth the Voice distinctly to as prodigious a Distance and Loudness.
For if the Stentoro-phonecon (which is but