A little later Francis Bacon writes:

'In the system of Copernicus there are many and grave difficulties; for the threefold motion with which he encumbers the earth is a serious inconvenience, and the separation of the sun from the planets, with which he has so many affections in common, is likewise a harsh step; and the introduction of so many immovable bodies into nature, as when he makes the sun and the stars immovable, the bodies which are peculiarly lucid and radiant, and his making the moon adhere to the earth in a sort of epicycle, and some other things which he assumes, are proceedings which mark a man who thinks nothing of introducing fictions of any kind into nature, provided his calculations turn out well.'

Bacon himself was very ignorant of all that had been done by mathematics; and, strange to say, he especially objected to astronomy being handed over to the mathematicians. Leverrier and Adams, calculating an unknown planet into a visible existence by enormous heaps of algebra, furnish the last comment of note on this specimen of the goodness of Bacon's view. . . . Mathematics was beginning to be the great instrument of exact inquiry; Bacon threw the science aside, from ignorance, just at the time when his enormous sagacity, applied to knowledge, would have made him see the part it was to play. If Newton had taken Bacon for his master, not he, but somebody else, would have been Newton. - De Morgan.

Copernicus cannot be said to have flooded with light the dark places of nature in the way that one stupendous mind subsequently did but still, as we look back through the long vista of the history of science, the dim Titanic figure of the old monk seems to rear itself out of the dull flats around it, pierces with its head the mists that overshadow them, and catches the first gleam of the rising sun, .

Like some iron peak, by the Creator

Fired with the red glow of the rushing morn.

- E. J. C. Morton.

TYCHO BRAHE (1546-1601). The first great need of the new Copernican astronomy - adequate and accurate data—was soon to be supplied by Tycho Brahe, born in 1546 of a noble Danish family. While a student at the University of Copenhagen his interest in astronomy was enlisted by an eclipse, and later, at Leipsic, he persisted in devoting to his new avocation the time

and attention he was expected to give to subjects more highly esteemed for a man of birth and fortune.

From a lunar eclipse which took place while he was at Leipsic, Tycho foretold wet weather, which also turned out to be correct.

Here, too, he began his life work of procuring and improving the best instruments for astronomical observations, at the same time testing and correcting their errors. Returning to Denmark from travels in Germany, his predilection for astronomy was powerfully stimulated by the appearance in the constellation Cassiopeia, in November, 1572, of a brilliant new star, which remained visible for 16 months. The great importance attached to this occurrence by Tycho and his contemporaries was due to the evidence it afforded against the truth of the Aristotelian conviction that the heavens were immutable, since Tycho's careful observations showed that the star must certainly be more distant than the moon, and that it had no share in the planetary motions. He reluctantly published an account of the new star, expressing still his adherence to the current pre-Copernican notions of crystalline spheres for the different heavenly bodies and of atmospheric comets, all combined with astrological reflections and inferences, as illustrated by the following passages from Dreyer's biography:

The star was at first like Venus and Jupiter, and its effects will therefore first be pleasant; but as it then became like Mars, there will next come a period of wars, seditions, captivity, and death of princes and destruction of cities, together with dryness and fiery meteors in the air, pestilence, and venomous snakes. Lastly, the star became like Saturn, and there will therefore, finally, come a time of want, death, imprisonment, and all kinds of sad things.

As the star seen by the wise men foretold the birth of Christ, the new one was generally supposed to announce His last coming and the end of the world.

That an unusual celestial phenomenon occurring at that particular moment should have been considered as indicating troublous times, is extremely natural when we consider the state of Europe in 1573. The tremendous rebellion against the Papal supremacy, which for a long time had seemed destined to end in the complete overthrow of

the latter, appeared now to have reached its limit, and many people thought that the tide had already commenced to turn.

Tycho considered that the new star was formed of 'celestial matter,' not differing from that of which the other stars are composed, except that it was not of such perfection or solid composition as in the stars of permanent duration. It was therefore gradually dissolved and dwindled away. It became visible to us because it was illuminated by the sun, and the matter of which it was formed was taken from the Milky Way, close to the edge of which the star was situated, and in which Tycho believed he could now see a gap or hole which had not been there before.

But the star had a truer mission than that of announcing the arrival of an impossible golden age. It roused to unwearied exertions a great astronomer, it caused him to renew astronomy in all its branches by showing the world how little it knew about the heavens; his work became the foundation on which Kepler and Newton built their glorious edifice, and the star of Cassiopeia started astronomical science on the brilliant career which it has pursued ever since, and swept away the mist that obscured the true system of the world. As Kepler truly said, 'If that star did nothing else, at least it announced and produced a great astronomer.'

At the same time the book bears witness to the soberness of mind which distinguishes him from most of the other writers on the subject of the star. His account of it is very short, but it says all there could be said about it that it had no parallax, that it remained immovable in the same place, that it looked like an ordinary star and it describes the star's place in the heavens accurately, and its variations in light and color. Even though Tycho made some remarks about the astrological significance of the star, he did so in a way which shows that he did not himself consider this the most valuable portion of his work. To appreciate his little book perfectly, it is desirable to glance at some of the other numerous books and pamphlets which were written about the star, and of most of which Tycho himself has in his later work given a very detailed analysis.

In 1575 Tycho obtained while travelling a copy of Copernicus' Commentariolus, and in the following year received from King Frederick II the island of Hveen, with funds for the maintenance of an observatory upon it. As to the former his opinion is that