gravitation, chemical affinity, or animal appetency, instead of ascribing them to a blind chance; the doctrine of atoms, as constituting or composing the material world by the variety of their combinations, so far from leading the mind to atheism, would strengthen the demonstration of the existence of a Deity, as the first cause of all things; because the analogy resulting from our perpetual experience of cause and effect would have thus been exemplified through universal nature.

The heavens declare the glory of GOD_, and the firmament sheweth his handywork!  One day telleth another, and one night certifieth another; they have neither speech nor language, yet their voice is gone forth into all lands, and their words into the ends of the world.  Manifold are thy works, O LORD! in wisdom hast thou made them all._ Psal. xix. civ.

* * * * *

SECT.  XL.

    On the OCULAR SPECTRA of Light and Colours, by Dr. R. W. Darwin, of
    Shrewsbury.  Reprinted, by Permission, from the Philosophical
    Transactions, Vol.  LXXVI. p. 313.

Spectra of four kinds. 1. Activity of the retina in vision. 2. Spectra from defect of sensibility. 3. Spectra from excess of sensibility. 4. Of direct ocular spectra. 5. Greater stimulus excites the retina into spasmodic action. 6. Of reverse ocular spectra. 7. Greater stimulus excites the retina into various successive spasmodic actions. 8. Into fixed spasmodic action. 9. Into temporary paralysis. 10. Miscellaneous remarks; 1. Direct and reverse spectra at the same time.  A spectral halo.  Rule to predetermine the colours of spectra. 2. Variation of spectra from extraneous light. 3. Variation of spectra in number, figure, and remission. 4. Circulation of the blood in the eye is visible. 5. A new way of magnifying objects.  Conclusion.

When any one has long and attentively looked at a bright object, as at the setting sun, on closing his eyes, or removing them, an image, which resembles in form the object he was attending to, continues some time to be visible; this appearance in the eye we shall call the ocular spectrum of that object.

These ocular spectra are of four kinds:  1st, Such as are owing to a less sensibility of a defined part of the retina; or spectra from defect of sensibility. 2d, Such as are owing to a greater sensibility of a defined part of the retina; or spectra from excess of sensibility. 3d, Such as resemble their object in its colour as well as form; which may be termed direct ocular spectra. 4th, Such as are of a colour contrary to that of their object; which may be termed reverse ocular spectra.