to the Medium, I know not how that, by any contrivance of Art, can advantage Direct Hearing, otherwise than I have declar'd already in the propagation or conveyance of Sounds, though to the Refracting or Reflecting of them it may very much conduce; of which presently.
And so I have done with the first part of my present undertaking, which is the Comparison of Direct Vision and Audition, as to their Improvements from Art. The rest follow. Wherefore,
II. Concerning Refracted Vision and its Comparison, I observe, That Refracted Vision is always made Ex parte Medii , as Reflected is ex parte Objecti . And therefore, though Direct Vision may be help'd ex parte Objecti, Medii vel Organi , yet Refracted can be improv'd only ex parte Medii , and Reflected ex parte Corporis oppositi alone. Unless it be in a mixt or compound Vision, that is Refracto-Reflext , when the reflext Rays pass to the Eye through a refracting Medium, such as the Medium Internum , contain'd in