18 OSCILLATIONS OF THE LUNAR TIDES. 



and are during other parts of that cycle confined 

 within 18 from the equator. 



178. It may here be observed that even if this 

 cycle of 149 years were absolutely exact, which it is 

 not, it would not suffice to determine a precise recur- 

 rence of lunar influence as far as the recurrence of 

 storms in particular localities is concerned. Because 

 for such a purpose we should have to take into con- 

 sideration the oscillations in longitude, which cause 

 the diurnal tides; which is a matter of detail which 

 does not concern us at present. We have for the 

 present to deal solely with oscillations in latitude: 

 and for this purpose the cycle of 149 years is suffi- 

 ciently precise : if at any solstice the greatest possible 

 amount of lunar declination from the equator occur, 

 then a similar extreme of declination will recur after 

 a period of 149 years. We will not at present inves- 

 tigate the intermediate cycles in which similar posi- 

 tions recur approximately: but will first consider 

 how the moon's different positions in declination in 

 each revolution round the earth will affect the annual 

 tide, and the solar tides. 



It will, however, be observed that as far as the 

 forces which we have hitherto investigated are con- 

 cerned; if at any period of the year the combined 

 action of those forces cause the occurrence of storms 

 at any particular localities on the earth's surface : 

 then, if at the same period in any other year, the 

 moon be twenty- four hours distant from the position 



