Fig. 7 — Graphs for Xinc; Stations superimposed for comparative purposes. 



Tlie e.xtreme similarity of (lie stations is striking, and is indicative of a general procees 

 not depentlent upon location factors. 



The curves no doubt wouid have been still morejregiilar if all of the analyses could 

 have oeen made on the same days, but this was impossible. 



