PREVIOUS WORK. 



207 



measure of the pressure changes at each station. Places having the same average pressure 

 amplitudes are connected by a series of lines called by Lockyer ' isanakatabars,' which are 

 found to run approximately parallel to the circles of latitude. The pressure amplitudes increase 

 from near the equator to C0° S. aiid thence decrease towards the Pole. As we are interested 

 only in the region south of latitude 40° S., we will limit our attention to this region. From 

 40° S. to 60° S., the pressure amplitudes increa.se and the average pressures decreases ; from 

 60° S. to the Pole, the pressure amplitudes decrease and pressure increases. 



It is then pointed out that this same relationship would hold if a series of cyclones 

 having their centres in latitude 60° S. passed from west to east, for the average pressure 

 would be low and the pressure amplitude high near the track of the centres, i.e., along lati- 

 tude 60° S. Lockyer gives reasons for believing that to the north of such a belt of cyclones 

 there would be a similar belt of anticyclones, while to the south of it there would be an 

 intense, but comparatively small (in area), anticyclone central about the South Pole. 



Figure 62, which is taken from Lockyer's monograph, represents his conclusions. Over the 

 Southern Ocean we see the belt of cyclones, each of which is of such a size that its southern 



Fig. 62. Lockjcr'a diagiam of pressure distribution. 



