But to remove all doubt, that this Inequality is caused by the Retardment of the Light, he demonstrates, that it cannot come from any Excentricity, or other Cause of those that are commonly alledged to explicate the Irregularities of the Moon, and the other Planets; though he be well aware, that the first Satellit of Jupiter was Excentrick; and that, besides his Revolutions were advanced or retarded, according as Jupiter did approach to or recede from the Sun; as also, that the Revolutions of the Primum Mobile were unequal: Yet, saith he, these three last Causes of Inequality do not hinder the first from being manifest.
An introductory Essay to the Doctrine of Sounds, containing some Proposals for the improvement of Acousticks; As it was presented to the Dublin Society, Nov. 12. 1683, by the Right Reverend Father in God Narcissus Lord Bishop of Ferns and Leighlin.
BEing to treat of the Doctrine of Sounds, I hold it convenient to premise something in the general, concerning this Theory; which may serve at once to ingage your Attention, and excuse my Pains, when I shall have recommended them, as bestow'd on a Subject not altogether useless and unfruitful.
And for this purpose I shall omit to speak any thing of the Excellency of the Matter in Hand; though it might be celebrated by Arguments drawn from several Topicks, and particularly from this, that new Discoveries and Improvements may be made, both as to the Generation, Propagation and Reception of Sounds into the Sense; which, in a peculiar manner agrees to this, above the Object of any other Sense whatsoever. I shall, I say, omit these things, and apply my self wholly to the Usefulness of the Theory, that we are now falling upon, which I think cannot better be discovered, than by making a comparison 'twixt the Senses of Seeing and Hearing, as to their Improvements. I mean, by shewing, that this latter of Hearing is capable of all those improvements which the Sense of Seeing has receiv'd from Art, besides many more advantages that the Ear may enjoy, by the help of our Doctrine, above the Eye; all which moreover will be of as great benefit to Mankind, as any thing that Opticks have yet discover'd, if not of greater; which, with some other pre-eminencies that it has upon another Score, will happily render Acousticks the nobler Science of the two.
In order to the making good what I but now premised of the Comparison of these two Faculties of Seeing and Hearing, as to their Improvements, I observe;
That Vision is threefold, Direct, Refracted, and Reflex'd; answerable whereunto we have Opticks, Dioptricks, and Catoptricks.
In like manner Hearing may be divided into Direct, Refracted and Reflex'd; whereto answer three parts of our Doctrine of Acousticks, which are yet nameless, unless we call them Acousticks, Diacousticks, and Catacousticks, or (in another Sense, but to as good Purpose) Phonicks, Diaphonicks, and Cataphonicks.
I. Direct Vision has been improv'd two ways, ex parte Objecti, and ex parte Organi vel Medii.
1. Ex parte Objecti, Direct Vision has receiv'd advantages by the Arts of Producing, Conserving and Imitating Light and Colours, which are the Objects of Vision.