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Show Of the Swimming of Fifli. 116 Chap. X X I I_ Filh having a inore delicate kind of Flelh, and lighter frame of Bones, are more ealily fupported in a more thick flurd Medium then thofe of Birds, which would be more readily hurried through the All: in a Central Moti. on toward the Ground, were it not enwrappcd within a light Coverture, which boyeth up the more weighty bodies of Fowls, in a thin fluid Medi. um. Fill} being a rare Contexturc, made up Without any articulation of Bones (except thofe of the Fpine) of Scales, Porous Flefli, light Vifcera, and liitcfinies (filled with a fmall proportion of thin Excrements, lodged in a Concave Body) receive many advantages of Swimming; fo that thefe fine dipper), Compages, being deflitute of genuine Refpiration, as defective in Lungs, do not always fwim near the iurface of the Water, but con. \‘erfc in the body of it, and chiefly in the bottom near the Earth, which fiipplietli them with the greateft part of their Aliment. Vx liercfore, becaufe Fifh now and then converfe in the middle, fome. tiiiiiimi ifi‘Illifxifcpiii. times near the Surface of the water, and other times near the Banks, or "‘i3""""'"‘" Shore , it is requilite they fhould have a power to transfer themfelves from one place to another, for the reception of Air and Aliment. (Sharp. XX III. "7' {pace of time, as handed with a fmaller or greater number ‘of Oats. Flat and broad Filh, as Turbit, Skait, Thornback,Flounders Bret, Soals, and the like, are left naked of greater Fins affixed to their Bodi es, and be- ing thin and Broad, are eafily fupported upon many Columns of Water and are fringed round with a kind of thin Membranous fubl'cance ( not altoj gether unlike Fins) by whofe appulfes upon the Water, and the aflil‘tanc e of the Tail, broad Filh {hoot themielves forward in a f'traight Courfe. And Fifh as well as Birds, and other Animals, have fimple and mix-- rimamar: ed Progreflive Motions, as right, upward, downward, and obliun as ricdintmpie tending toward the right and left, and Circular, in turning the Body in1 ma 323$;de fercnce to a Retrograde Motion. _ The motion from the bottom of the Water to the top, is guided by the Fins and Tail, making firoaks directly downward upon the Water ( lodged underneath) by whole impulfe the body of the Filh is immediately mounted upward toward the ambient parts of the Water, and Fifh are aéted in a contrary Motion downward by their weight (and by a fmall help of their Fins, foanewhat refiing upon the Water) producing a Central Momen And when they make approaches to the Surface of the water, there are more Inltruments required) and greater appulfes made upon the water in the afceut of Filh from the bottom to the top, and fo moved forward in a direct Line, then to be kept quiet, and circumfcribed with one conftant Sur- ing to the riiiht by the afliftance of the left Fin acting more vigoroufly and chiefly by inclination of the Tail tending to the left, which draweth the face of Water, which may be obtained with lefs labour, only by the dilata- Body toward the right, or by bending the Tail toward the richt, which pub And Filh in mixed Motions, are carried in oblique Lines, either by bond Trasfon‘cwliat tion of their Fins (fomewhat refembling wings, in ufe and figure) which letli ire body to the left, by reafon the Tail of Filh refemb'leth a Rudder "" -n ,6 give a flop to Central Motion, in fuftaining the Filh immoveable in the to freer the body of Fifh either in order to Simple Motionin a firaight courfe' 1 (_ {yum Medium to a iuperior, or to lhoot them forward in a right Line, the one 3 body of the water, but to raife up Filh from the inferior region of a fluid liloticn. Tenfinnmfi Biggfggm 13:15:53: or in mixed Motion obliquely, and quite round in 3 Circular manner rd an oppofite point, in reference to a Retrograde Motion. requireth a more foft, the other a more impetuous motion of the Fins, which are performed by multiplied alternate motions of Tenfion and Flexion; the firlt being ordained in favour of the fecond, as the Tenfors are minifterial to the Flexors of the Fins and Tails, making {troaks upon the wa- Fi‘iieaiitl'l'ails ter, which do thicken it and force it backward, by Whofe refiltance, the m ""1" Head and Body are carried forward; and they are carried upward by their C H A P. Pins and Tails prefling {trongly downward againft the water, by whofc Renitence and Elafiick power they mount upward toward the Surface of X XIII. 0f the Creeping of flm'ma/r. the water. v Thcanalngy And Birds hold great analogy in their flight in the Air, with the Swim- 3:23;:31‘miniiig of Filhin the water ; in which Palm-footed Birds, Whofe feet interming. fperfed with Membranes, have much refemblance with the Fins of Fill], which being Expanded make appulfes upon the water preffed backward, by whofe fpringy difpolition, both Filh and Fowl are driven forward in Swimming and Flying. The WNW And the Mediums in which Birds and Filh do Hie and fwim, "do correof "3'1"? aml fpond with each other in likenefs, as being both fluid 9 but in this they diféi‘c‘tiiighdfii; agree, that the water is more folid and vifible, and doth more eaiily fuflzain fggl‘fi‘ffim Filh, then Air doth Birds, which is occafioned by its greater thinnefs and rarity : And on the other lide, water being a more denfe body, is more calily Conglobated by the Vibrations of their Fins and Tails upon the water rep1elled backward, whofe impulfe draweth the bodies of Filh from place to p ace. $21,011,335 V\ hereupon Fifh are dteifed with more or lefs Fins (according to th6 'Sf""§‘,‘,",§; n "'1'th tlifiétent makes of their Bodies) by which they are malter of greater or lefs quickncfs in SWimming, as Boats make fewer or more Miles in fuch 3 ‘ {pace int 0 1C3. ANother kind of Progreflive Motion, is that of Creeping, (6%"ng to be the ineanefi of all, wherein Animals deftitute of Le and Feet to fupport them, do Creep along fweeping the Ground With the r Bellies in a kind of Undulating .Motion Upon the Surface of the Earth and do move laterally in divers Arches, made fometimes to the right, and fometimes to the left fide; which is celebrated by feveral Machin es of Crecpingin 5:333:35» mc‘pi"3‘h°l‘ gaming: iigfiorni'ccci otion i feared on each fide of thefe Reptiles, and fixed to the fides of the pine, confiliing of many Vertebtes, from which divers fhort Mufcles do arife and into which they are inferted; and by contraéting themfelves toward the f-Iead 1‘1) Al‘bl'C‘Viate the Body, bymaking feveral feginent s of Circles alternately, 31321313 :11:Each fidc, thereby drawrng the Body forward, part by part, as [hep by 523:??? Sothat Creeping is acted by many Flexions not made by Angles; left mm the Ligaments tying the Vertebres of the Spine togethe r fhould be Lacera- ted, and a-[axatiori be made: whereupon the Motion of Reptiles, is ma- naged by divers flrong ihort Mufclcs, bending the Body into many arched Pofitions, |
