Living pictures; their history, photoproduction and practical working. With a digest of British patents and annotated bibliography (1899)

FEESiSTJi:yc£: of vision. 3 as already mentioned, Persistence of Vision, and from this point we make our departure; the investigations and theories respecting the cause of this effect, whether residing in the brain-cells' slow return (after their excitation) to normal state, or connected with the nature of the stimulus experienced by the terminal of the optic nerve in the retina, are all interesting; but they do not alter the experimental fact of persistence, which is certainly true, even though all the theories hitherto promulgated with respect to it should prove to be erroneous. A sentence, which is probably the first written refer- ence to persistence of vision, is contained in the fourth book of " De rerum natura," by Lucretius, dated about 65 B.C. He there says: " This [perception cf movement] is to be explained in the following way; that when the first image passes off, and a second is afterwards produced in another position, the former then seems to have changed its gesture. This we must conceive to be done by a very rapid process," etc. Though seemingly so very a propos this passage is in reality only a reference to a theory of dreams, and its interest arises from the fact that Dr. Plateau found it quoted against him (by Dr. Sinsteden) on the inven- tion of the phenakistoscope; and it seems of some interest as being the first-quoted anticipation of the first living picture apparatus. Indeed Lucretius only expresses the fact of persistent vision and mentions no apparatus for its demonstration. This matter appears to have been first treated of two centuries later in the second book of Ptolemy's Optics. This work, written about the year 130 A.D., narrowly escaped annihilation; only two copies are known to exist, and these are both Latin translations through the Arabic. One copy is in the Bibliotheque Nationale in Paris, the other and more perfect example is in the