Of this Opinion also was Bartholine Anat. l. 3. c. 8. and divers other eminent Anatomists.
But Dr. Briggs is of Opinion that the Adnata, and the other Muscles sufficiently answer all those Ends ascribed to that Muscle by former Anatomists, and thinks Probabiliùs itaque esse hunc Musculum nervi Optici actionem (per vices) confirmare, nè à prono Brutorum incessu & copioso affluxu humorum debilitetur, Ophthal. c. 2. §. 2.
The Musculus Suspensorius being in the Porpess, as well as Brutes, Dr. Tyson thinks the Use of it is not to suspend the Bulk of the Eye; but rather by its equal Contraction of the Sclerotis, to render the Ball of the Eye more or less Spherical, and so fitter for Vision. Tyson’s Anat. of the Porpess, p. 39.
[t] Musculus obliquus inferior oritur à peculiari quodam foramine in latere Orbitæ ocularis facto, (contra quam in cæteris, &c.) quo fit ut ex unâ parte à Musculo trochleari, ex alterâ verò ab hujus Musculi commodissimâ positione, Oculus in æquilibrio quodam constitutus, irretorto obtutu versus objecta feratur, nec plus justo accedat versus internum externumve canthum; quæ quidem Libratio omnino nulla fuisset, absque hujus Musculi peculiari originatione (cujus ratio omnes hucusque Anatomicos latuit). And so this curious Anatomist goes on to shew farther the stupendous Artifice of the great Creator in this Position of the Oblique Muscles. Brigg’s Nova Vis. Theor. p. 11. meo libro.
[] Besides those particular Motions which the Eye receives from the Oblique Muscles, and I may add its Libration also in some Measure, some Anatomists ascribe another no less considerable Use to them; namely, to lengthen and shorten the Eye (by squeezing and compressing it) to make it correspond to the Distances of all Objects, according as they are nigh or far off. Thus the ingenious Dr. Keil; The Aqueous Humour being the thinnest and most liquid, easily changeth its Figure, when either the Ligamentum Ciliate contracts, or both the Oblique Muscles squeeze the middle of the Ball of the Eye, to render it Oblong when Objects are too near us. Keil’s Anat. Chap. 4. Sect. 4. See [Note (y).]
[w] Quis verò opifex præter Naturam, quâ nihil potest esse callidiùs, tantam solertiam persequi potuisset in Sensibus? quæ primùm Oculos membranis tenuissimis vestivit, & sepiit; quas primum perlucidas fecit, ut per eas cerni posset: firmas aurem, ut continerentur. Cic. de Nat. Deor. l. 2. c. 57.
[x] Boyl of Final Causes.
[y] It is easy to be observed, that the Pupil openeth in dark Places; as also when we look at far distant Objects, but contracts by an Increase of Light, and when the Objects are nigh. This Motion of the Pupil some say, is effected by the circular and strait Fibres of the Uvea, and some attribute it to the Ligamentum Ciliare. Yet I have no great doubt but that they both concur in that Action, and that the Ligamentum Ciliare doth, at the same time the Pupil opens or shuts, dilate or compress the Crystalline, and bring it nigher unto, or carry it farther off the Retina. For the Structure of the Ligamentum Ciliare, and its two Sorts of Fibres, drawn with the Help of a Microscope, I shall refer to Mr. Cowper’s Anat. T. 11.
[z] In Bove, Caprâ, Equo, Ove, & quibusdam aliis elliptica est (Pupilla) ut eo magis in hisce forsan animalibus, quæ prono incessu victum in agris quæritant, radios laterales ad mala & incommoda utrinque devitanda admittat. Briggs’s Ophthal. c. 7. §. 6.
Homini erecto, aliisque, &c. caput erigere, & quaquaversus circumspicere solitis, plurima simul objecta, tum suprà, tum infrà, tum è latere utroque——visu excipiuntur; quapropter Oculi Pupilla rotunda esse debet.——Attamen bovi, &c. caput ferè semper pronum——gerentibus, tantùm quæ coràm, & paulo à latere obversantur, intuitu opus est: quapropter Pupilla——oblonga est, &c. Willis de Anim. Brut. p. 1. c. 15.