So that we see, that though it has pleas’d the All-wise Creator, to indue this creature with such multitudes of eyes, yet has he not indued it with the faculty of seeing more then another creature; for whereas this cannot move his head, at least can move it very little, without moving his whole body, biocular creatures can in an instant (or the twinkling of an eye, which, being very quick, is vulgarly used in the same signification) move their eyes so as to direct the optick Axis to any point; nor is it probable, that they are able to see attentively at one time more then one Physical point; for though there be a distinct Image made in every eye, yet ’tis very likely, that the observing faculty is only imploy’d about some one object for which they have most concern.

Now, as we accurately distinguish the site or position of an Object by the motion of the Muscles of the eye requisite to put the optick Line in a direct position, and confusedly by the position of the imperfect Picture of the object at the bottom of the eye; so are these crustaceous creatures able to judge confusedly of the position of objects by the Picture or impression made at the bottom of the opposite Pearl, and distinctly by the removal of the attentive or observing faculty, from one Pearl to another, but what this faculty is, as it requires another place, so a much deeper speculation. Now, because it were impossible, even with this multitude of eye-balls, to see any object distinct (for as I hinted before, onely those parts that lay in, or very neer, the optick Lines could be so) the Infinitely wise Creator has not left the creature without a power of moving the head a little in Aerial crustaceous animals, and the very eyes also in crustaceous Sea-animals; so that by these means they are inabled to direct some optick line or other against any object, and by that means they have the visive faculty as compleat as any Animal that can move its eyes.

Distances of Objects also, ’tis very likely they distinguish, partly by the consonant impressions made in some two convenient Pearls, one in each cluster; for, according as those congruous impressions affect, two Pearls neerer approach’d to each other, the neerer is the Object, and the farther they are distant, the more distant is the Object: partly also by the alteration of each Pearl, requisite to make the Sensation or Picture perfect; for ’tis impossible that the Pictures of two Objects, variously distant, can be perfectly painted, or made on the same Retina or bottom of the eye not altered, as will be very evident to any one that shall attentively consider the nature of refraction. Now, whether this alteration may be in the Figure of the Cornea, in the motion of access or recess of the Retina towards the Cornea, or in the alteration of a crystalline humour, if such there be, I pretend not to determine; though I think we need not doubt, but that there may be as much curiosity of contrivance and structure in every one of these Pearls, as in the eye of a Whale or Elephant, and the almighty’s Fiat could as easily cause the existence of the one as the other; and as one day and a thousand years are the same with him, so may one eye and ten thousand.

This we may be sure of, that the filaments or sensative parts of the Retina must be most exceedingly curious and minute, since the whole Picture it self is such; what must needs the component parts be of that Retina, which distinguishes the part of an object’s Picture that must be many millions of millions less then that in a man’s eye? And how exceeding curious and subtile must the component parts of the medium that conveys light be, when we find the instrument made for its reception or refraction to be so exceedingly small? we may, I think, from this speculation be sufficiently discouraged from hoping to discover by any optick or other instrument the determinate bulk of the parts of the medium that conveys the pulse of light, since we find that there is not less accurateness shewn in the Figure and polish of those exceedingly minute lenticular surfaces, then in those more large and conspicuous surfaces of our own eyes. And yet can I not doubt, but that there is a determinate bulk of those parts, since I find them unable to enter between the parts of Mercury, which being in motion, must necessarily have pores, as I shall elsewhere shew, and here pass by, as being a digression.

As concerning the horns FF, the feelers or smellers, GG, the Proboscis HH, and I, the hairs and brisles, KK, I shall indeavour to describe in the 42. Observation.

Observ. [XL]. Of the Teeth of a Snail.

I have little more to add of the Teeth of a Snail, besides the Picture [Schem. 25.]
Fig. 1. of it, which is represented in the first Figure of the 25. Scheme, save that his bended body, ABCDEF, which seem’d fashioned very much like a row of small teeth, orderly plac’d in the Gums, and looks as if it were divided into several smaller and greater black teeth, was nothing but one small bended hard bone, which was plac’d in the upper jaw of the mouth of a House-Snail, with which I observ’d this very Snail to feed on the leaves of a Rose-tree, and to bite out pretty large and half round bits, not unlike the Figure of a (C) nor very much differing from it in bigness, the upper part ABCD of this bone, I found to be much whiter, and to grow out of the upper chap of the Snail, GGG, and not to be any thing neer so much creas’d as the lower and blacker part of it HIIHKKH which was exactly shap’d like teeth, the bone growing thinner, or tapering to an edge towards KKK. It seem’d to have nine teeth, or prominent parts IK, IK, IF, &c. which were join’d together by the thinner interpos’d parts of the bone. The Animal to which these teeth belong, is a very anomalous creature, and seems of a kind quite distinct from any other terrestrial Animal or Insect, the Anatomy whereof exceedingly differing from what has been hitherto given of it I should have inserted, but that it will be more proper in another place. I have never met with any kind of Animal whose teeth are all join’d in one, save onely that I lately observ’d, that all the teeth of a Rhinocerot, which grow on either side of its mouth, are join’d into one large bone, the weight of one of which I found to be neer eleven pound Haverdupois. So that it seems one of the biggest sort of terrestrial Animals, as well as one of the smallest, has his teeth thus shap’d.

Observ. [XLI]. Of the Eggs of Silk-worms, and other Insects.