igo 



DISCOVERY REPORTS 



SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC 

 I I I I I I I I I I I I I I I I 



50- 



4 



3 0- 



50- 



50 -54 S 



50- 



40- 



3-0- 



2 0- 



I I I I I I I I I I I I I I I I 



SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNt JULY AUG SEPT OCT NOV DEC 



Fig. 6 A-E. Variations of the middle temperature of the convergence gradient. Averages from Table 4 are shown as black 

 dots when based on three or more records, and as rings when based on one or two. The curves in Figs. A-D are reproduced 

 on one temperature scale in Fig. E. 



