" The investigation described in the subsequent pages bears close relation to three sciences. It was approached by the author from the standpoint of astronomy and a desire to understand the variations of the sun. It was hoped that these variations could be more accurately studied by correlation with climatic phenomena. But the science of meteorology is still comparatively new and supplies us only with a few decades of records on which to base our conclusions. So botanical aid was sought in order to extend our knowledge of weather changes over hundreds and even thousands of years by making use of the dependence of the annual rings of trees in dry climates on the annual rainfall. If the relationship sought proves to be real, the rings in the trunks of trees give us not only a means of studying climatic changes through long periods of years, but perhaps also of tracing changes in solar activity during the same time. Thus astronomy, meteorology, and botany join in a study to which each contributes essential parts and from which, it is hoped, each may gain a small measure of benefit. "

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