Wherefore the now describ'd new Tube-spectacles, contributing so much to the help and preservation of Sight, may well be counted an improvement of Direct Vision, because they convey the Rays to the Eye without any kind of Refraction whatsoever. Seeing the same Object also through various holes, plac'd at certain distances, does somewhat alter Vision; but of this perhaps more hereafter.
Now as Direct Vision has thus been improved, so likewise Direct Hearing partly has already receiv'd, and partly may by the Doctrine whereof we are treating, (if well cultivated) farther receive as great and notable Improvements, both ex parte Objecti, and ex parte Organi vel Medii.
1. As to the Object of Hearing, which is Sound, improvement has been and may be made, both as to the Begetting, and as to the Conveying and Propagating (which is a kind of Conserving) of Sounds.
1. As to the Begetting of Sounds. The Art of imitating any Sound, whether by Speaking (that is pronouncing) any kind of Language, (which really is an Art, and the Art of Speaking, perhaps one of the greatest) or by Whistling, or by Singing (which are allow'd Arts) or by Hollowing or Luring (which the Huntsman or Faulkner would have to be an Art also) or by imitating with the Mouth (or otherwise) the Voice of any Animal, as of Quails, Cats, and the like; or by representing any Sound begotten by the Collision of Solid Bodies, or after any other manner; these are all Improvements of Direct Hearing, and may be improv'd.
Moreover the Skill to make all sorts of Musical Instruments, both Ancient and Modern, whether Wind Instruments or String'd, or of any other sort, whereof there are very many (as Drums, Bells, the Systrum of the Egyptians, and the like) that beget (and not only propagate) Sounds; the Skill of making these, I say, is an Art, that has as much improv'd Direct Hearing, as an Harmonious Sound exceeds a single and rude one, that is, an immusical Tone; which Art is yet capable of farther improvement. And I do hope, that by the Rules, which may happily be laid down concerning the Nature, Propagation and Proportion, or Adapting of Sounds, a way may be found out, both to improve Musical Instruments already in use, and to invent new ones, that shall be more sweet and luscious, than any yet known. Besides that, by the same means Instruments may be made, that shall imitate any Sound in Nature, that is not Articulate, be it of Bird, Beast, or what thing else soever.
2. The Conveying and Propagating (which is a kind of Conserving) of Sounds, is much help'd by duly placing the Sonorous Body, and also by the Medium.
For if the Medium be Thin and Quiescent, and the Sounding Body plac'd conveniently, the Sound will be easily and regularly propagated, and mightily conserv'd. I say,
1. If the Medium be Thin and Quiescent, because it otherwise causes a Refracted Sound, of which afterwards. Hence in a still Evening, or the dead of the Night (when the Wind ceases) a Sound is better sent out, and to a greater distance than otherwise, tho' much of this may be ascrib'd to its Refraction also.
2. I say, that the Sonorous Body must be plac'd conveniently, near a Smooth Wall, near Water, or a Plain, whose Surface is even.
1. Near a Smooth Wall, either Plain or Arch'd (Cycloidically or Elliptically, rather than otherwise, tho' a Circular or any Arch will do, but not so well.)