Intelligence and Miscellaneous Articles. 465 



of these groups is given by the following numbers : — 



millim. 



1st group, X = 0005183 (Angstrom's determination), 



2nd „ \=0'00038378 (Cornu's „ ), 



3rd „ X = 0-0003335 (Mascart's „ ). 



xt 4.u *.& x. , ^ . . i. 0-0005183 . 



Now the ratio between the first two numbers, , is 



O'OOOooo/o 



nearly identical with the ratio between the wave-lengths of the hy- 

 drogen-lines C and F, lines which Mr. Stoney regards as the 20th 

 and 27th harmonics of one and the same fundamental vibration. 

 The first two groups of magnesium also might therefore be regarded 

 as the 20th and 27th harmonics of a fundamental group of vibrations, 

 of which the w T ave-length, for the least-refrangible line, would be 

 00103660 millim. As to the third group, it would not represent 

 the 32nd harmonic (as this is done by the hydrogen-line h), but, 

 very nearly, the 31st. 



Facts of the same kind are found also for the lines of cadmium 

 which have been determined by M. Mascart *. Thus the ratio of 

 the wave-length of the 1st line (X=0-00064370) to that of the 18th 

 (\=0-00025742)' is exactly as 5 to 2. Further, between the 2nd 

 line of cadmium (X=0'0005377) and the 8th (\= 0*0003985 6) the 



. 27 . 



ratio ^~ is found, with an approach to accuracy very near the lim't 



of the errors of observation. These two lines might, then, be re- 

 garded as the 20th and 27th harmonics of one and the same funda- 

 mental vibration. The 32nd harmonic is not found ; but, as in the 

 case of magnesium, the 31st harmonic nearly coincides with the 10th 

 line (X=000034645). The 6th line (X = 0*00046765) represents 

 very exactly the 23rd harmonic of the same fundamental. Finally, 



27 



the 6th and 10th lines are also connected by the same ratio of ^r. 



It seems difficult to admit these coincidences to be fortuitous ; 

 and probably others still would be discovered on a closer examina- 

 tion of the question.- — Bibliotheque Universelle, Archives des Sciences 

 Physiques et Naturelles, September 15, 1871. 



ON THE ELECTROMOTIVE FORCE OE INDUCTION IN LIQUID CON- 

 DUCTORS. BY DR. L. HERMANN. 



On the occasion of experiments on the excitation of the nerve by 

 induction in itself, which I shall elsewhere communicate, the ques- 

 tion suggested itself whether the electromotive force of the induction 

 demonstrated by Faraday in liquid conductors was the same as that 

 in metallic ones, other conditions being the same. Since under 



* Annates de I'Ecole normale, 1867, vol. iv. p. 28. 

 Phil. Mag. S. 4. Vol. 42. No. 282. Dec. 1871. 2 H 



