Page:Popular Science Monthly Volume 5.djvu/551

Rh when fuel is supplied to it. The sun was, then, to the ancient world, a kind of supernatural phenomenon, interest in which partook more of the uninquiring awe due to an immediate miracle of Deity, than of the curiosity excited by a fact of the natural world; and whatever we may think of such a way of regarding the matter, the view of the ancient philosophy, that the sun was an immaculate orb of pure fire, self-sustained, continued to be accepted almost as a dogma of the faith down to times subsequent to the dawn of the modern philosophy.

When one of the first, possibly the first, of the observers of sunspots, Christopher Scheiner, a Jesuit, communicated his discovery to his provincial, the latter, Mr. Proctor relates, answered: "I have read Aristotle's writings from beginning to end, many times, and I can assure you I have nowhere found in them any thing similar to what you mention; go, therefore, my son, tranquillize yourself, be assured that what you take for spots in the sun are the faults of your glasses or your eyes."

Perhaps we are, however unconsciously, ourselves in some degree Aristotelians in such matters, and it is at least certain that the unrecognized influence of ancient modes of thought has delayed progress in solar physics, by preparing astronomers to admit theories which they could not have accepted with a clear recognition of the fact that physical laws are the same in the sun as here, however erroneously we learn them from our limited terrestrial experience. In the hypothesis of Wilson, for instance, that exhaustless flow of solar light and heat is made to come from a shallow stratum of brilliant cloud, surrounding a dark and presumably cold and solid globe. The elder Herschel adopts this hypothesis, with slight modification (it is not yet quite dislodged from the text-books), and even his eminent son appears to feel nothing like an imperious demand for a sustaining cause of the almost infinite flood of heat his own researches showed that these clouds must be giving.

It seems now extraordinary that men justly eminent as the Herschels could rest satisfied with an hypothesis which so evaded the consideration of the fundamental problem of the equality of the solar radiation, by tacitly assuming the suspension there of the most familiar laws of terrestrial experience.

The views now generally accepted contemplate the sun as hot throughout its mass, and in such a mass as containing indubitably an enormous though finite reservoir of heat. And, if, so far at least, there is an agreement even among those who differ as to the way in which this heat originated and is maintained, much is due to astronomers like Faye, who have insisted on this recognition of the need of accounting for the equable emission of heat with a success which may make us underrate our obligations to them, as this need, once enunciated, is so clear as to seem a truism, though it was far from being such till a very recent period.