NOMOS. 87 



tained its highest pitch of velocity, the slide of the 

 camera is raised, and the spark passed. The whole 

 is the work of an instant ; but there has been suf- 

 ficient time to copy, not only the wheel, but also the 

 inscription on the spoke. Now this copying must 

 have been instantaneous, for if it had not been so 

 the image would have been blurred by the motion of 

 the wheel. The copying, also, must have been in- 

 stantaneous, because the illumination was only in- 

 stantaneous. There can, indeed, be no more beautiful 

 illustration of the companionship between electrical 

 light and chemical action than this; while at the 

 same time the fact is well calculated to spiritualise, 

 as it were, our conceptions of chemical action, and, 

 by displaying its amazing subtleness and swiftness, 

 to show its fitness for electrical purposes. Now the 

 nerve of sight is endowed with the power of per- 

 ceiving light, and this perception is the only notion 

 it can form of any kind of action. In the operation 

 for cataract, for example, the patient suffers pain as 

 the knife divides the outer coat of the eye, but the 

 sensation of pain is exchanged for that of light as 

 soon as the instrument has penetrated to the retina 

 or true visual surface. In this case the same action 

 is attested by pain in one part of the frame, and by 

 light in another part; and if so, why should Jit be 

 otherwise in the case of electricity ? What reason 

 is there that the same action which produces the 

 shock in the nerves of common sensation and in the 

 muscles should not produce the sensation of light in 

 the eye ? There is no such reason to be met with, 

 and, as there is not, the natural presumption is that 



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