More and more the science seeks to discover periodicities and to correlate these with others.
Many attempts have been made to correlate the results of the analyses of a soil with its known cropping power, but there is yet much to be learnt in regard to these matters.
It is tempting to try to correlate the members of this triad with the individual members of the older triad.
How the hostile kings of Israel and Syria came to fight a common enemy, and how to correlate the Assyrian and Biblical records, are questions which have perplexed all recent writers.
It is unfortunately still very difficult to correlate even approximately the strata on the two sides of the Atlantic, and there is great doubt as to what strata belong to each division of the Tertiary period even in different parts of North America.