Hay 3, 1918] 



SCIENCE 



439 



concentrated solution of its own ions at the 

 bottom, and small crystals of tin will form 

 upon it in the dilute solution at the top. 



The specific inductive capacity of the water 

 solution must be much higher than that of 

 the ether solution, even after being decreased 

 by the ions in solution, since that of pure water 

 at room temperature is more than 75 while 

 that of ether is less than 4.5. 



The results are quite as striking when lead 

 acetate is dissolved in the water and ether 

 and a lead wire is used for the electrode as 

 the tin with stannous chlorida No doubt 

 any salt that is slightly soluble in ether may 

 be used just as successfully as those named 

 above 



Fernando Sanford 



Stanford University 



hering's contributions to physiological 



OPTICS 



To THE Editor of Science : In your issue of 

 April 19, page 388, you announce the death of 

 Professor Dr. Ewald Hering and refer to him 

 as " the eminent physiologist." Permit me to 

 add that his chief work, for which he became 

 well known, was in physiological optics and 

 more especially the perception of color by the 

 eye; his work in this direction is well-known 

 and has been frequently referred to in litera- 

 ture in which it was coupled with that of the 

 famous Helmholz, with whom he was for a 

 time a contemjjorary. 



Early in 1911 he was knighted, at the same 

 time that Professor Roentgen was, by having 

 conferred upon him the decoration of the 

 Order " Pour le Merite " for his creditable work 

 and scientific researches. A description of his 

 collection of experiments demonstrating phe- 

 nomena in physiological optics, some of which 

 the writer has had the pleasure of seeing in his 

 own laboratories in Liepzig and Prague, would 

 make very interesting and instructive reading 

 and ought to be published. 



In one of these a band of light was thrown 

 on a screen, which every one without hesita- 

 tion would acknowledge was a bright green 

 when, as a matter of fact, there was absolutely 

 no green present; the sensation of green light 

 was a purely physiological eflfect due to a 



neighboring band of its complementary color. 

 This peculiar phenomenon has suggested to the 

 writer that there might perhaps be some way 

 of utilizing it to advantage in supplying an 

 additional color to colored moving pictures. 

 Carl Herinq 

 Philadelphia, 



reform of the world's calendar 



To THE Editor of Science: In Science of 

 April 19 appears a paper advocating " A Com- 

 mon Sense Calendar," by Professor How- 

 ard C. Warren of Princeton University. The 

 changes proposed by Professor "Warren would 

 certainly prove a great improvement over the 

 present highly archaic calendar that the world 

 is burdened with as a heritage from our re- 

 mote ancestors. But Professor Warren's 

 scheme could be farther simplified. 



The subject of a reform in the calendar was 

 agitated quite widely some half dozen years 

 ago; and about five years ago an international 

 commission charged with the consideration of 

 this subject was located in Berne, Switzerland. 

 This commission sent out invitations to all 

 who cared to do so, to submit suggestions upon 

 the question of reforming the calendar, and 

 this writer had the temerity to offer a scheme 

 for a new calendar. 



This scheme embodies one very radical 

 change, which if accepted would reduce the 

 problem to the last degree of simplicity, to wit, 

 the division of the year into thirteen lunar 

 months of four complete weeks, or twenty- 

 eight days each. It was proposed to inter- 

 calate a thirteenth month (with the suggested 

 name of Sol) between July and August of the 

 existing calendar. 



The extra day in each year should be dis- 

 iwsed, as suggested by Professor Warren, that 

 is, inserted between the last day of the old and 

 the first day of the new year. The year might 

 be made to begin on a day more in accord 

 with nature's harmonies, that is, in the begin- 

 ning of spring instead of the middle of win- 

 ter ; but that is not a vital matter. The extra 

 day to be dealt with every fourth year, to be 

 called " Leap Day," might be conveniently in- 

 serted bewteen two of the summer months. 



