44 



THE CHRISTIAN PHILOSOPHER. 



and hesitation, &quot; Where is God my Maker ?&quot; 

 He is in us, and around us, directing every 

 movement in our animal frame to act in harmony 

 with the surrounding elements, and to minister 

 to our enjoyments ; and it is only when his ex 

 quisite operations are deranged by external vio 

 lence, that we feel inconvenience or pain. 



Such are only a few general outlines of the 

 structure of the eye: for no notice has been 

 taken of the numerous minute veins, arteries, 

 nerves, lymphatics, glands, and many other par 

 ticulars which are connected with this organ. 

 But all this delicate and complicated apparatus, 

 in the structure of the eye, would have been of 

 no use whatever for the purpose of vision, had 

 not a distinct substance been created to act upon 

 it, exactly adapted to its nature and functions. 

 In order that the eye might serve as the medium 

 of our perceptions of visible objects, light was 

 formed, and made to travel from its source at 

 the rate of 195,000 miles in a second of time. 

 This prodigious velocity of light is, doubtless, es 

 sential to the nature of vision ; since it actually 

 exists, and since we find that it radiates with the 

 same swiftness from the most distant visible star, 

 as from the sun which enlightens our system. 

 To abate the force of this amazing velocity, 

 its particles have been formed almost infinitely 

 small a circumstance which alone prevents this 

 delightful visitant from becoming the most tre 

 mendous and destructive element in nature. Dr. 

 Nieuwentyt has computed, that, in one second of 

 time, there flows 418,660,000,000,000,000,000,- 

 000,000,000,000,000,000,000,000* particles of 

 light out of a burning candle, which number con- 

 tainsat least 6,337,242,000,000 times the number 

 of grains of sand in the whole earth, supposing 

 every cubic inch of the eanh to contain a million 

 of grains. It has been justly remarked, by Mr. 

 Ferguson and other authors, that &quot; if ihe particles 

 of light were so large, that a million of them 

 were equal in bulk to an ordinary grain of 

 sand, we durst, no more open our eyes to the 

 light, than suffer sand to be shot point blank 

 against them, from the mouth of a cannon.&quot; It 

 may also be remarked, that the property which 

 all bodies possess, of reflecting light, is essen 

 tial to the purpose of vision, without which, the 

 splendid and variegated scene of nature would 

 be changed into a dreadful gloom ; and were the 

 rays of light of one uniform colour, and not com 

 pounded of various hues, one object could not 

 be distinguished from another, and the beauti 

 ful aspect of our globe would instantly disappear. 



Thus we see, that the eye is adapted to light, 

 and light to the eye ; and in this admirable 

 adaptation the wisdom of the Creator is er&amp;gt;Uinerly 

 displayed. For light has no effect upon me ear, 

 or upon any other organ of sensation ; so as to 



See Appendix, No. V 



produce a perception of visible objects ; as, on 

 the other hand, the undulations of the air have n& 

 effect upon the eye, so as to produce the sensa 

 tion of sound. The eye did not produce the 

 light, nor did the light form the eye ; they arts 

 perfectly distinct from each other, yet so nicely 

 adapted in every particular, that had any one 

 quality or circumstance been wanting in either, 

 the functions of vision could not have been per 

 formed in the manner in which they now operate, 

 which strikingly demonstrates, that one and the 

 same Intelligent Being, possessed of a wisdom 

 beyond our comprehension, formed the curious 

 structure of the eye, and endued the rays of light 

 with those properties of colour, motion, and mi 

 nuteness, which are calculated, through the me 

 dium of this organ, to produce, in sentient beings, 

 the ideas of visible objects. And, surely, he 

 never intended that such exquisite skill and con 

 trivance should be altogether overlooked by ra 

 tional beings, for whose pleasure and enjoyment 

 all this benevolent care is exercised. 



Manner in which vision is performed. 



Let us now attend a little to the manner in 

 which vision is performed, by the medium of 

 light acting on the organs of sight. If we take 

 a common convex glass a reading glass for ex 

 ample and hold it at some distance from a 

 candle or a window sash, placing a piece of 

 white paper behind the glass, at the distance of 

 its focus, the image of the candle or sash will be 

 painted on ihe paper, in an inverted position. 

 This experiment may be performed, with a better 

 effect, by darkening a room, and placing the con 

 vex glass in a hole cut out of the window shutter, 

 when the rays of light flowing from the objects 

 without, and passing through the glass, will forma 

 picture of the objects opposite the window, on the 

 white paper, adorned with the most beautiful co 

 lours. In a manner similar to this, are the images 

 of external objects depicted on the back part 

 of the inner coat or membrane of the eye. The 

 rays of light, proceeding in all directions, from 

 surrounding objects, and falling on the eye, are 

 transmitted through the pupil ; arid being refract 

 ed by the different humours, (particularly by the 

 crystalline humour, which acts the part of a con 

 vex lens,) they converge to a focus on the retina, 

 where the images of visible objects are painted in 

 an inverted position ; and, by means of the optic 

 nerve, these images are conveyed to the mind. 



The following figure will perhaps more dis 

 tinctly illustrate this point. Let a, b, c, x, y, 

 represent the globe of the eye, and A, B, C, an 

 object at a certain distance from it. Now, it is 

 well known that every point of a visible object 

 sends out rays of light in all directions ; and, 

 therefore, a certain portion of the rays which 

 flow from the object ABC, will fall upon the 

 cornea^ between x and y, and, passing through the 



