736 THE POPULAR SCIENCE MONTHLY. 



vertical columns, while another series of arches and uprights, darker 

 than the general ground, appeared, intersecting the former, so as to 

 have the dark uprights just intermediate between the bright ones of 

 the first set. On the second occasion the pattern consisted of a very- 

 slender and delicate hoop, surrounded with a set of circles of the same 

 size, as tangents to the centre circle and to one another. On the third 

 occasion the whole visual area was covered with separate circles, each 

 having within it a four-sided pattern of concave circular arcs. All 

 these phenomena were much fainter than in the chloroform exhibition." 



The accuracy of these descriptions will be readily admitted, as far 

 as my own observations have enabled me to judge. I am, however, 

 disposed to believe that the forms under which the spectra present 

 themselves vary persistently in different individuals to a considerable 

 extent. 



A question now naturally arises : What are these spectra, and how 

 are they formed ? 



An eminent scientific authority has suggested to me that they are 

 possibly referable to that obscure mental process which Dr. Carpenter 

 has termed " unconscious cerebration.'''' (See "Human Physiology.") 

 But, allowing this to be the case, the questions put by Sir John Her- 

 schel still remain unanswered : 



" Where do the patterns or their prototypes in the intellect origi- 

 nate ? 



" If it be suggested that a kaleidoscopic power of forming regular 

 patterns, by the combination of casual elements, exists in the sensorium, 

 how is it that we are unconscious of the power unable to use it vol- 

 untarily only aware of its being exerted at times in a manner in 

 which we have actually no part but as spectators ? " 



I cannot help thinking that more than one of the most ancient 

 types of symbolism upon which so much learning and ingenuity have 

 been expended in endeavors to invest them with mystical meanings, or 

 to trace their origin in the forms of the organic world, may have been 

 first suggested by these hitherto-unnoticed spectra. 



But besides these geometrical forms, there are others, which I 

 must again describe in Sir John Herschel's words : 



" I fancy," he writes, " that it is no very uncommon thing for per- 

 sons in the dark, and with their eyes closed, to see, or seem to see, 

 faces and landscapes. I believe I am as little visionary as most people, 

 but the former case very frequently happens to myself. The faces 

 present themselves voluntarily, are always shadowy and indistinct in 

 outline, for the most part unpleasing, though not hideous, expressive 

 of no violent emotions, and succeeding one another at short intervals 

 of time, as if melting into each other. Sometimes ten or a dozen ap- 

 pear in succession, and have always, on each separate occasion, some- 

 thing of a general resemblance of expression, or some peculiarity of 

 feature common to all, though very various in individual aspect and 



