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FIG. 60.
Tins is a matter of absolute certainty; proved by what is called, in technical language, the northern and southern declination, which is simply saying that the sun's path is nearest the polar centre in summer, and farthest away from it in winter.
At noon, on the 21st of any December, let a rod be so fixed that on looking along it, the line of sight touches the lower edge of the sun. For several days this line of sight will continue nearly the same, showing that the sun's path for this period is little changed; but on the ninth or tenth day to touch the sun's lower edge, the rod will have to be lifted several degrees towards the zenith. Every day afterwards until the 22nd of June, the rod will have to be raised. On that date there will again be several days without any visible change; after which, day by day, the rod must be lowered until the 21st December. In this simple way it may be demonstrated that the sun's path gets larger every day from December 21st to June 22nd; and smaller every day from June 22nd to December 21st, of every year.
From a number of observations made by the author during the last twenty-five years, it is certain that both the minimum or June path of the sun, and maximum or December path have been gradually getting farther from the northern centre. The amount of expansion is very small,
but easily detected; and if it has been going on for centuries, which seems consistent with known phenomena, it explains at once and perfectly, the fact that England as well as more northern latitudes have once been tropical. There is abundant evidence that the conditions and productions now found within the tropics, have once existed in the northern region, which is now so cold and desolate, and inimical to ordinary animal and vegetable life. Hence it is a proper and logical conclusion that the sun's path was once very near to the earth's arctic or polar centre.
The following diagram, fig. 60, will show the sun's peculiar
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FIG. 60.
path, N represents the polar centre, A the sun in its path in June; which daily expands like the coils of the mainspring of a watch, until it reaches the outer and larger path B, in December, after which the path gradually and day by day con-tracts until it again becomes the path A, on the 21st of June.
That such is the sun's annual course is demonstrable by actual observation; but if it is asked why it traverses such a peculiarly concentric path, no practical answer can be given, and no theory or speculation can be tolerated. At no distant period perhaps, we may have collected sufficient matter-of-fact evidence to enable us to understand it; but until that occurs, the Zetetic process only permits us to say:--"The peculiar motion is visible to us, but, of the cause, at present we are ignorant."
