[a] Besides their absolute Necessity, and great Use to the World, there are several Topics, from whence the Waters may be demonstrated to be God’s Work; as, the creating so vast a Part of our Globe; the placing it commodiously therein, and giving it Bounds; the Methods keeping it sweet and clean, by its Saltness, by the Tides, and Agitations by the Winds; the making the Waters useful to the Vegetation of Plants, and for Food to Animals, by the noble Methods of sweetning them; and many other Things besides, which are insisted on in that Part of my Survey.
[] Pliny having named divers Mirabilia Aquarum, to shew their Power; then proceeds to their Uses, viz. Eædem cadentes omnium terrâ nascentium causa fiunt, prorsus mirabili naturâ, siquis velit reputare, ut fruges gignantur, arbores fruticesque vivant, in cœlum migrare aquas, animamque etiam herbis vitalem inde deferre: justâ confessione, omnes terra quoque vires aquarum esse beneficii. Quapropter ante omnia ipsarum potentia exempla ponemus: Cunctas enim quis mortalium enamerare queat? And then he goes on with an Enumeration of some Waters famed for being medicinal, or some other unusual Quality. Plin. L. 31. c. 1. & 2.
[c] Pliny reckons 176 Kinds in the Waters, whose Names may be met with in his L. 32. c. 11. but he is short in his Account.
[d] Pliny, L. 9. c. 3. saith, that in the Indian Sea there are Balenæ quaternûm jugerum (i.e. 960 Feet) Pristes 200 cubitorum (i.e. 300 Feet.) And L. 32. c. 1. he mentions Whales 600 Foot long, and 360 broad, that came into a River of Arabia. If the Reader hath a mind, he may see his Reason why the largest Animals are bred in the Sea, L. 9. c. 2.
[e] As the largest, so the most minute Animals are bred in the Waters, as those in Pepper-water; and such as make the green Scum on the Waters, or make them seem as if green, and many others. See [Book IV. Chap. 11. Note (n), (v).]
[f] It might be here shewn, that the Bodies of all the several Inhabitants of the Waters are the best contrived and suited to that Place and Business in the Waters, which is proper for them; that particularly their Bodies are cloathed and guarded, in the best Manner, with Scales, or Shells, &c. suitable to the Place they are to reside in, the Dangers they may there be exposed unto, and the Motion and Business they are there to perform: That the Center of Gravity (of great Consideration in that fluid Element,) is always plac’d in the fittest Part of the Body: That the Shape of their Bodies, (especially the more swift,) is the most commodious for making Way through the Water, and most agreeable to geometrical Rules; and many other Matters besides would deserve a Place here, were they not too long for Notes, and that I shall anticipate what will be more proper for another Place, and more accurately treated of there.
[g] See before [Book IV. Chap. 11.]
[h] Galen was aware of the Respiration of Fishes by their Branchiæ. For having said, that Fishes have no Occasion of a Voice, neither respire through the Mouth as Land Animals do, he saith, Sed earum, quas Branchias nuncupamus, constructio, ipsis vice Pulmonis est. Cùm enim crebris ac tenuibus foraminibus sint Branchiæ hæ interceptæ, aëri quidem & vapori perviis, subtilioribus tamen quàm pro mole aquæ; hanc quidem extra repellunt, illa autem promptè intromittunt. Galen de Us. Part. L. 6. c. 9. So also Pliny held, that Fishes respired by their Gills; but he saith Aristotle was of a different Opinion. Plin. L. 9. c. 7. And so Aristotle seems to be in his Hist. Animal. L. 8. c. 2. and in other Places. And I may add our famous Dr. Needham. See his De form. Fœtu, Chap. 6. and Answer to Severinus.
[] A protuberant Eye would have been inconvenient for Fishes, by hindring their Motion in so dense a Medium as Water is; or else their brushing through so thick a Medium would have been apt to wear, and prejudice their Eyes; therefore their Cornea is flat. To make amends for which, as also for the Refraction of Water, different from that of the Air, the wise Contriver of the Eye, hath made the Crystalline spherical in Fishes, which in Animals, living in the Air, is lenticular, and more flat.
[k] As I have shew’d before, that the Bodies of Birds are nicely pois’d to swim in the Air; so are those of Fishes for the Water, every Part of the Body being duly balanc’d, and the Center of Gravity, (as I said in [Note (f)]), accurately fix’d. And to prevent Vacillation, some of the Fins serve, particularly those of the Belly; as Borelli prov’d by cutting off the Belly-fins, which caus’d the Fish to reel to the right and left Hand, and render’d it unable to stand steadily in an upright Posture.