392 



SCIENCE. 



[N. S. Vol. IX. No. 220. 



the front cams elevates the balls, whereas 

 a rise of the rear cams depresses them, the 

 two component waves will meet in the same 

 phase at the origin when the long axes of 

 the eccentrics there point horizontally away 

 from each other, i. e., when the front 

 pointer is to the front or left of the opera- 

 tor at the crank, and the rear pointer to his 

 right. This is also the null position, or zero 

 of phase (to be marked + 0), for the first 

 particle of each component wave, i. e., the 

 particle on the left hand (origin) of the 

 observer facing the machine in front. Both 

 component harmonic curves and the com- 



of both axles over 1, 2 and 3 right angles, 

 while the compound harmonic is shoved 

 forward \, ^, f wave- length. Further rota- 

 tion of 90° restores the original case. 



If the two cam axles contain the same 

 number of turns, the same phase difference 

 obviously corresponds to all particles. Other- 

 wise special consideration is necessary for 

 each case. 



Restoring the front and rear cam axles 

 to their original positions (pointers horizon- 

 tally outward), rotate the rear axle 90°, 

 clockwise, relative to the other. This puts 

 all its particles 90° ahead in phase of the 



Table of Phase Differences. Clockwise Rotation of Axles, Positive. Displacements of 

 HOLES Upward and Ebaewaed, Positive. 



pound harmonic leave the origin with a 

 descending node, the head of the wave 

 (right semi-wave) being a crest. Absence 

 of phase difference in the component har- 

 monics of the particle at the origin will 

 occur for other cardinal positions of the 

 pointers, viz : front and rear pointers re- 

 spectively up and down (maxima, marked 

 + m) , right and left or towards each other 

 (mean position marked — 0), and down 

 and up (minima, marked — m). These 

 follow each other on like clockwise rotation 



corresponding particles of the front wave. 

 The pointers in their cardinal positions will 

 now be respectively left and down, up and 

 left, right and up, down and right to the 

 operator, etc., for successive additional rota- 

 tions of 90° each. 



Beginning again with pointers away from 

 each other, i. e., with both component, S. H. 

 motions starting at the first particle, let the 

 front axle be rotated clockwise 90° rela- 

 tively to the other. The pointers in their 

 cardinal positions will now be up and right, 



