( 52 ) 
Temp. aN Eene | tomo Pot. Vol. Pressure. 
| 
30°,23 | 4182 | 5251 | 41°45 | 1179 58,10 
(eontin.)| 0993 | 55,61 |(eontin)| 0993 62,47 
0797 | 58,24 0800 67,27 
0560 | 60,48 0571 73,93 
0399 «| 68,04 
520,5 2613 37,40 
412,45 | 2445 37,29 | 9498 39,59 
2285 39,12 2168 43,03 
2100 11,48 1921 46,90 
1910 44,18 1662 51,70 
1727 47,04 1187 63,13 
1545 50,42 0936 | 71,12 
1362 54,08 0758 | 77,77 
Physics. — “The elementary theory of the Zeeman-effect. Reply 
to an objection of Poincaré.” By Prof. H. A. Lorentz. 
§ 1. In a recent article in L’Eclairage Electrique !) PoINcARÉ 
comes to the conclusion that the well known theory of ZrEMAN’s 
phenomenon, according to which every luminous particle contains 
either a single movable ion, or a certain number of such ions whose 
vibrations are mutually independent, can account for the doublet 
which is seen along the lines of force, but is unable to explain 
the triplet which one observes in a direction perpendicular to these 
lines. This result is obtained by treating, not the emission but the 
absorption in the magnetic field, and it is curious that the same 
mode of reasoning has led Vorer ®) to formulae implying the existence 
of the triplet. I believe this discrepancy to be due to POINCARE’s 
erroneously omitting the term 
1) PorscarÉ, La théorie de Loruntz et le phénomène de ZEEMAN, Kelairage Élec- 
trique, T. 19, p. 5, 1899. 
2) Vorer, Ueber den Zusammenhang zwischen dem ZEEMAN’schen und dem Fa- 
rapay’schen Phänomen, Göttinger Nachrichten, 1898, Heft 4, p. 1. 
