body repercussing be a good distance off: for if it be near, and yet not so near as to make a concurrent echo, it choppeth with you upon the sudden. It is requisite likewise that the air be not much pent: for air at a great distance pent, worketh the same effect with air at large in a small distance. And therefore in the trial of speaking in the well, though the well was deep, the voice came back suddenly, and would bear the report but of two words. 249. For echos upon echos, there is a rare instance thereof in a place which I will now exactly describe. It is some three or four miles from Paris, near a town called Pont-Charenton; and some bird-bolt shot or more from the river of Sein. The room is a chapel or small church. The walls all standing, both at the sides and at the ends. Two rows of pillars, after the manner of aisles of churches, also standing; the roof all open, not so much as any embowment near any of the walls left. There was against every pillar a stack of billets above a man's height; which the watermen that bring wood down the Sein in stacks, and not in boats, laid there, as it seemeth, for their ease. Speaking at the one end, I did hear it return the voice thirteen several times; and I have heard of others, that it would return sixteen times: For I was there about three of the clock in the afternoon: and it is best, as all other echos are, in the evening. It is manifest that it is not echos from several places, but a tossing of the voice, as a ball, to and fro; like to reflections in looking-glasses, where if you place one glass before and another behind, you shall see the glass behind with the image, within the glass before; and again, the glass before in that; and divers such super-reflections, till the species speciei at last die. For it is every return weaker and more shady. In like manner the voice in that chapel createth speciem speciei, and maketh succeeding super-reflections; for it melteth by degrees, and every reflection is weaker than the former : so that if you speak three words, it will, perhaps, some three times report you the whole three words; and then the two latter words for some а a a times; and then the last word alone for some times; still fading and growing weaker. And whereas in echos of one return, it is much to hear four or five words; in this echo of so many returns upon the matter, you hear above twenty words for three. 250. The like echo upon echo, but only with two reports, hath been observed to be, if you stand between a house and a hill, and lure towards the hill. For the house will give a back echo; one taking it from the other, and the latter the weaker. 251. THERE are certain letters that an echo will hardly express; as S for one, especially being principal in a word. I remember well, that when I went to the echo at Pont-Charenton, there was an old Parisian, that took it to be work of spirits, and of good spirits. For, said he, call Satan, and the echo will not deliver back the devil's name; but will say, va t'en ; which is as much in French as apage, or avoid. And thereby I did hap to find, that an echo would not return S, being but a hissing and an interior sound. 252. Echos are some more sudden, and chop again as soon as the voice is delivered ; as hath been partly said : others are more deliberate, that is, give more space between the voice and the echo; wbich is caused by the local nearness or distance: some will report a longer train of words, and some a shorter ; some more loud, full as loud as the original, and sometimes more loud, and some weaker and fainter. 253. WHERE echos come from several parts at the same distance, they must needs make, as it were, a choir of echos, and so make the report greater, and even a continued echo; which you shall find in some hills that stand encompassed theatre-like. 254. It doth not yet appear that there is refraction in sounds, as well as in species visible. For I do not think, that if a sound should pass through divers mediums, as air, cloth, wood, it would deliver the sound in a different place from that unto which it is deferred; which is the proper effect of refraction. ; But majoration, which is also the work of refraction, appeareth plainly in sounds, as hath been handled at full, but it is not by diversity of mediums. Experiments in consort touching the consent and dissent between visibles and audibles. WE have obiter, for demonstration's sake, used in divers instances the examples of the sight and things visible, to illustrate the nature of sounds: but we think good now to prosecute that comparison more fully. Consent of visibles and audibles. 255. BOTH of them spread themselves in round, and fill a whole floor or orb unto certain limits; and are carried a great way: and do languish and lessen by degrees, according to the distance of the objects from the sensories. 256. BOTH of them have the whole species in every small portion of the air, or medium, so as the species do pass through small crannies without confusion: as we see ordinarily in levels, as to the eye; and in crannies or chinks, as to the sound. 257. BOTH of them are of a sudden and easy generation and dilation; and likewise perish swiftly and suddenly; as if you remove the light, or touch the bodies that give the sound. 258. BOTH of them do receive and carry exquisite and accurate differences; as of colours, figures, motions, distances, in visibles; and of articulate voices, tones, songs, and quaverings, in audibles. 259. BOTH of them, in their virtue and working, do not appear to emit any corporal substance into their mediums, or the orb of their virtue; neither again to raise or stir any evident local motion in their mediums as they pass; but only to carry certain spiritual species; the perfect knowledge of the cause whereof, being hitherto scarcely attained, we shall search and handle in due place. 260. BOTH of them seem not to generate or produce any other effect in nature, but such as appertaineth to their proper objects and senses, and are otherwise barren. 261. But both of them, in their own proper action, do work three manifest effects. The first, in that the strongest species drowneth the lesser; as the light of the sun, the light of a glow-worm; the report of an ordnance, the voice: The second, in that an object of surcharge or excess destroyeth the sense; as the light of the sun the eye; a violent sound near the ear the hearing: The third, in that both of them will be reverberate; as in mirrors, and in echos. 262. Neither of them doth destroy or hinder the species of the other, although they encounter in the same medium; as light or colour hinder not sound, nor e contra. 263. Both of them affect the sense in living creatures, and yield objects of pleasure and dislike: yet nevertheless the objects of them do also, if it be well observed, affect and work upon dead things; namely, such as have some conformity with the organs of the two senses; as visibles work upon a looking-glass, which is like the pupil of the eye; and audibles upon the places of echo, which resemble in some sort the cavern and structure of the ear. 264. Both of them do diversly work, as they have their medium diversly disposed. So a trembling medium, as smoke, maketh the object seem to tremble, and a rising or falling medium, as winds, maketh the sounds to rise or fall. 265. To both, the medium, which is the most propitious and conducible, is air; for glass or water, etc. are not comparable. 266. In both of them, where the object is fine and accurate, it conduceth much to have the sense intentive and erect; insomuch as you contract your eye when you would see sharply; and erect your ear when you would hear attentively; which in beasts that have ears moveable is most manifest. 267. The beams of light, when they are multiplied and conglomerate, generate heat; which is a differ а ent action from the action of sight: and the multiplication and conglomeration of sounds doth gene rate an extreme rarefaction of the air; which is an action materiate, differing from the action of sound; if it be true, which is anciently reported, that birds with great shouts have fallen down. Dissents of visibles and audibles. 268. The species of visibles seem to be emissions of beams from the objects seen, almost like odours, save that they are more incorporeal: but the species of audibles seem to participate more with local motion, like percussions, or impressions made upon the air. So that whereas all bodies do seem to work in two manners, either by the communication of their natures, or by the impressions and signatures of their motions; the diffusion of species visible seemeth to participate more of the former operation, and the species audible of the latter. 269. The species of audibles seem to be carried more manifestly through the air than the species of visibles : for I conceive that a contrary strong wind will not much hinder the sight of visibles, as it will do the hearing of sounds. 270. THERE is one difference above all others between visibles and audibles, that is the most remarkable, as that whereupon' many smaller differences do depend: namely, that visibles, except lights, are carried in right lines, and audibles in arcuate lines. Hence it cometh to pass, that visibles do not intermingle and confound one another, as hath been said before; but sounds do. Hence it cometh, that the solidity of bodies doth not much hinder the sight, so that the bodies be clear, and the pores in a right line, as in glass, crystal, diamonds, water, etc. but a thin scarf or handkerchief, though they be bodies nothing so solid, hinder the sight: whereas, contrariwise, these porous bodies do not much hinder the hearing, but solid bodies do almost stop it, or at the least ats tenuate it. Hence also it cometh, that to the reflection of visibles small glasses suffice; but to the reverberation of audibles are required greater spaces, as hath likewise been said before. 271. VISIBLES are seen farther off than sounds are |