# Cycles Index: Data Bases

The following table of cycle period lengths is taken from the publication “Cycles Classic Library Collection” published by the Foundation for the Study of Cycles. The numbers after the cycle series name are page references to the "Cycles Classic Library Collection."

Some notes on the table are relevant. It was scanned and converted by OCR from a printed book and as such may contain some errors. Please report any errors that you find. The period lengths are sometimes stated as a whole number of years, which may mean that the cycle period is not known accurately or that the period was close to a whole number of years. In other cases periods such as 3.33 years are given which may mean about 3 and 1/3 years which is presumably more accurate than a whole number of years. There seems to be a tendency to use 1/2, 1/3 and 1/6 of years, perhaps because these are whole numbers of months. In that case the accuracy may be about 1 month. In other cases (most notably Dewey’s analysis) the periods are stated with more decimal palces and probably does truly reflect the accuracy of the results, e.g. 5.92 or 5.537 years.