From Cycle Synchronies: The Interrelationships of Physical, Biological, Social, and Economic Cycles, a handbook published by the Foundation for the Study of Cycles in Irvine, California. According to the handbook, “cycle scientists” have long been aware of the “curious” fact that cycle durations found in one area of study are often found in other, unrelated areas. The authors suggest that “at least some of the correspondences may not be accidental.”

The Four-year Cycle
(cycles of exactly 4.0 years)

Stock prices, U.S.A., 1837–1958
Moody’s index of industrial bond yields (all grades), U.S.A., 1919–1963
Plankton yields, Lake Michigan, 1926–1942
Cheese consumption, 1867–1953
Sunspots, 1749–1954
Arctic fox abundance, Canada, 1872–1931
Employment in non-agricultural establishments, 1944–1958
Pork prices, Germany, 1896–1930
Salmon abundance
UFO sightings, U.S.A., 1947–1969
Snowy owl migrations and abundance
Field mouse abundance, 1863–1936
Ruffed grouse abundance, New England Industrial output, U.S.A., 1944–1958

The Eight-year Cycle
(cycles from 7.96 to 8.02 years)

Lynx abundance, Canada, 1735–1951
Crude petroleum production, U.S.A., 1861–1964
Sweet potato production, U.S.A., 1868–1964
Precipitation, Philadephia, 1820–1964
Red squirrel abundance, New England, 1926–1938
Purchasing power of eggs, U.S.A., 1873–1936
Barometric pressure, the Alps, 1865–1918
Stock prices, U.S.A., 1831–1964
Butter, price per pound in New York, 1830–1966

The Nine-year Cycle
(cycles from 8.95 to 9.15 years)

Death rates in Massachusetts, 1860–1962
Gold production, U.S.A., 1835–1964
Deposits of all banks, U.S.A., 1934–1966
Woodcock abundance, Sussex, England, 1847–1931
Episcopal Church, U.S.A., new membership, 1849–1950
Freight traffic on the Canadian Pacific Railway, 1918–1940
Irish potato production, 1866–1964
Cattle on farms, U.S.A., 1867–1965
Pig-iron shipments, U.S.A., 1846–1964
Life insurance sales, U.S.A., 1854–1964
Bituminous coal production, U.S.A., 1800–1964
Sugar prices, wholesale, U.S.A., 1700–1964

The Fifty-four-year Cycle
(cycles from 52 to 56 years)

Shipbuilding, U.S.A., 1800–1952
Wheat prices, Europe, 1545–1868
International war battles, 1700–1913
Coal production, worldwide, 1873–1914
Exports, France, 1810–1914
Rainfall, England, 1727–1927
Thickness of Arizona tree rings, 1872–1941
Oat acreage, France
Interest rates, U.S.A.
Wages of agricultural workers, England, 1790–1920
Sunspots, 1700–1965