Page:Popular Astronomy - Airy - 1881.djvu/51

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LECTURE I.
37

however, have used several bright stars, whose relative positions have been well ascertained; and this is now the more usual course.

The methods of which I have spoken, give us the means of recording, with the greatest accuracy, the position of any object as viewed from any point of the earth, and we come to the same conclusions, as to the relative positions of the stars, wherever we may be placed. Thus, at the Cape of Good Hope, where there is an Observatory in the highest order, the relative positions of the stars are seen to be precisely the same as when they are viewed from the European Observatories. If you observe how many hours, minutes, and seconds, one star is before the other when it passes the meridian, and how many degrees, minutes, and seconds, one star is higher than the other when it passes the meridian—whether it it is observed here or at the Cape of Good Hope, it amounts to precisely the same thing there is not the slightest difference. From this we must draw one of two conclusions: either that the stars are, as it were, stuck in a shell of a very great size; or else, that the distance between the North of Europe and the Cape of Good Hope is unmeasureably small, compared with the distances of the stars; or that the distance of the stars is unmeasurebly great as compared with the distance from the North of Europe to the Cape of Good Hope.

I shall now conclude this lecture. In the next lecture I shall treat of the figure and dimensions and rotation of the earth; of the movements of the Sun amongst the stars; and of the motions of the planets.