740 Prof. H. E. Armstrong on Low-Temperature Research 



Society, the paper was referred, among others, to Sir Charles Wheat- 

 stone, who was mj intimate personal friend. Wheatstone was an 

 <3minently fair man and a good judge but the discovery did not then 

 recommend itself to his mind. For a whole Sunday afternoon we 

 walked on Barnes Common, discussing the experiments and their 

 -consequences, if true, to science. But all my arguments were in- 

 sufficient to convince my friend ; and I fear that then the Royal 

 Society did not appreciate and publish the researches." 



Unfortunately, even now the Royal Society has not improved its 

 methods and still submits all communications to an often ineffective 

 ^nd sometimes intolerant criticism, even dictating alterations which 

 are greatly resented by workers. The system is one which creates a 

 maximum of friction and affords a minimum guarantee against the 

 admiss'on of matter which has no special value. 



Chemical Action of Light. 



In the first of two lectures on the " Physiological Action of Light " 

 -which he delivered at the Institution on Friday, February 5, 1875, 

 Mr. James Dewar described in detail a long series of refined experi- 

 inent«, made in conjunction with Dr. McKendrick, to determine the 

 •effect of light on the electromotive force of the retina and optic 

 nerve. It was found to alter it to the extent of from 3 to 10 per 

 •cent, of the total amount of the natural current, the action on the 

 -compound eye of the Crustacea being the same as on the simple eye. 

 The alteration of the electrical effect as the luminous intensity is 

 varied appears to be closely in accordance with Fechner's law that the 

 difference of our sensations is proportional to the logarithm of the 

 luminous intensities by which they are provoked. 



In a second lecture on the same subject, on Friday, March 31, 

 1876, Prof. Dewar showed that yellow light, which is known to have 

 the greatest luminous effect, is also the most effective in producing 

 the electrical alteration. A method was then demonstrated of 

 working with live animals which involved merely a slight abrasion 

 of the skin on the surface of the head and connexion of the electrodes 

 with this and the eye surface. Warm and cold-blooded animals were 

 shown to behave alike. Finally, it was proved that the current 

 superadded or induced by the action of light is always in the one 

 ■direction — being added to the primary current when the course is 

 positive and the brain negative and subtracted from it when the 

 -course is negative and the brain positive. When two similar eyes 

 are placed in reversed positions on the electrodes, the galvanometer 

 deflection is to the right or left according to the eye affected. 



On March 29, 1878, in the first Friday evening lecture delivered 

 after his appointment as Fullerian Professor, ProfT Dewar dealt with 



