312 



SCIENCE 



[N. S. Vol. XLVI. No. 1187 



color with the letters of the alphabet. This 

 faculty has been called " Pseudo-chromses- 

 thesia," which, I take it, means sensitiveness to 

 false colors. It has been misunderstood by 

 writers, who have imagined that the peculiar 

 individuals having this trait actually see the 

 color on the letter, which is not the fact. It is 

 a mental association, not a false vision. Some 

 have attributed it to a recollection of color 

 blocks from which letters have been learned. 

 To the " pseudochromsesthetic " this explana- 

 tion is nonsense. It is, however, a fact that 

 tie tendency of this association of letters with 

 colors is hereditary, and that it goes with a cer- 

 tain interest in word-using and in the use of 

 color, features capable in each case of devel- 

 opment. 



When my son Eric was eight years old, no 

 one ever having spoken of it to him before, I 

 asked him what is the color of A? He re- 

 sponded at once that it is red. At that time, 

 1912, I made out a list of the alphabet with 

 the colors assigned to each. Quite recently 

 (1917) I repeated the question, never having 

 mentioned the matter since. He said at once 

 that A was red and seemed slightly surprised 

 that any one should not see the difference in 



innate color between red A and yellow E. 



A few changes appeared, however, in his 

 chromatic scale. These seem, however, to indi- 

 cate vagueness of color, as the same impres- 

 sion might be described as bluish in one case 

 and greenish or gray in another. For the sake 

 of those this note may interest, I append my 

 own chromatic scale which has not changed 

 appreciably since I first thought of it, with 

 those of two former students, the one my own 

 niece, Marjorie Edwards (now Mrs. Frank 

 Blake), and Edith Snow, daughter of the late 

 Dr. Frank Snow, former president of the Uni- 

 versity of Kansas. David St.vrr Jordan 



A SIMPLE DEMONSTRATION FOR EULER'S DY- 

 NAMICAL EQUATIONS 



Teachers of analytic mechanics may per- 

 haps be interested in a demonstration which I 

 have used for the past two years and which 

 seems to illuminate Euler's equations for the 

 rotation of a rigid body. The experiment is so 

 simple that it has doubtless been used before, 

 but I do not recall ever seeing it described. 



GH is an ordinary support rod some 70 cm. 

 long. IJ is a suspending cord. The ring I is 

 set at such a point that when the rod is at rest 



