176 DR. S. CHAPMAN ON THE LUNAR DIURNAL MAGNETIC VARIATION, ETC. 



The seasonal and synodic changes in this variation are discussed, and also the change 

 during the anomalistic month (from apogee to perigee). But the result in the latter 

 case is (in the words of the author) disappointing, as no clear progression is made 

 out, presumably owing to the somewhat small amount of material used for discussion. 

 Such apparent change as the data show is a retardation from apogee to perigee, but 

 this cannot be relied on. This first attempt to settle the point mentioned on p. 1G8 

 is therefore inconclusive, and further work on it is desirable. 



The effect of lunar declination on the tide is also dealt with by WAGNER, without 

 any decided result. Since a tidal effect may be regarded as due to a moon and anti- 

 moon, one of which will be in Northerly declination when the other is Southerly, and 

 rice versa, it does not seem probable that any explanation of the perigee-apogee 

 magnetic phase change is to be found in the variation of lunar declination. 



