EXPLANATION OF THK TABLES. 21 



show whether the line is to be classed as having small, medium, or large separation, and for this reason 

 the inclusion of such lines is justified. 



When measurements are given for both the n- and the /^-components, the weight for each is given, 

 separated by a comma. In case only the /"-component is measured, a dash before the comma indicates 

 the omission of the weight for the K-component. 



5. V.\LUES OF AX. 



The fifth and sixth columns of the tables contain the separation in Angstrom units of the components 

 given by light vibrating respectively perpendicular and parallel to the lines of magnetic force. (See 

 foot-note, p. 19.) When there is an even number of components for the same polarization, measurements 

 are made between the members of each pair which presents itself. A single value in one of these columns 

 means that one pair of components is present. When there are two or more pairs, the largest separa- 

 tion is given first, but the innermost pair is designated "Pair I." When there is an odd number of com- 

 ponents, any outer ones that may appear are measured from the central component, instead of being 

 treated as pairs, and the values are listed beginning with the outermost on the violet side, the presence 

 of a central component being indicated by 0.000. No attempt is made to give the relative intensity of 

 the n- and /^-components, as this depends largely upon the optical system. However, if there are more 

 than two components for the same polarization, the relative intensity of the pairs (or of each component 

 when there is an odd number) is given in parentheses after the value of the separation. 



If either AX column is blank for a certain hne, this indicates that a single, sharp component appears 

 for this polarization. Thus for all clear triplets, the /^-component column is blank. If, however, the 

 ^-component is unresolved, but widened so as to indicate that a higher field would separate it into two 

 or more, the letter "w" with subscript i, 2, or 3 is used to show the degree of widening. Components 

 marked "W2" or "ws" as a rule are certainly compound. A slight widening, which probably means more 

 than one component, is indicated by "w,," but this may in some cases result from the diffuse character 

 of the no-field line. 



There are many cases, especially in the ^-component column, where a measurement is given, followed 

 by "w" with a subscript. This means that a pair is measured, but each member of the pair is widened and 

 probably compound. If the widening is uniform, there are probably two or more components of equal 

 intensity. If the constituents of the widened component are of ditTerent intensity the component is 

 shaded toward one side. Such a line has the degree of widening given and in addition is denoted in 

 the "Remarks" column as "fringed" when each component shades off from the center, or as having 

 "inner fringes" when the shading is toward the center. 



The letters "n.m." indicate that a separation exists but is not measurable, usually by reason of the 

 faintness of the components. In such cases it is possible, as a rule, to tell the character of the separation 

 with fair certainty and the line is included on this account. Thus a faint but sharp /)-component com- 

 bined with traces of two sharp w-components is given as a triplet. The designation "n.m.w." is used 

 when the components are hazy as well as faint. 



6. Valxjes of AX/X^ 



Since in most points relating to the theory of the Zeeman phenomenon, the values of AX/X- rather 

 than of AX are considered (p. 4), the former quantity is entered in the seventh and eighth columns, 

 the positions of the numbers in the column being the same as that of the corresponding values of AX. 

 When X is in Angstrom units, the values given for AX/X- are to be multiplied by 10 *. 



