It appears from these results that the Zeeman effect is a much more complex phenomenon than was at first supposed, and therefore the simple explanation that was given above no longer applies. At any rate, it must be very seriously modified in order to account for the much more highly complex characterFIG. 85 of the phenomena, as here described. The complete theory has not yet been worked out, and meanwhile we must gather whatever information we can concerning the behavior of as many different radiations as possible. Every attempt to deduce some general law which will cover all cases at present known has thus far proved unsuccessful. There are a number of anomalies which seem even more difficult to account for than the doubling of this middle line and the multiplication of the side lines. For example, in one of the radiations examined, the line without any magnetic field appeared as quadruple, but when the magnetic field was on, it appeared as a single line.

There are quite a number of other interesting cases, which we have not time to consider now. The explanation of these anomalies will probably not be given until long after the explanation of the doubling and tripling and multiplication of separate lines.

The examination of spectral lines by means of the interferometer, while in some respects ideally perfect, is still objectionable for several reasons. In particular, it requires a very long time to make a set of observations, and we can