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

'The Ptolemean system was too complicated, and the new one which that great man Copernicus had proposed, following in the footsteps of Aristarchus of Samos, though there was nothing in it contrary to mathematical principles, was in opposition to those of physics, as the heavy and sluggish earth is unfit to move, and the system is even opposed to the authority of Scripture.'

URANIBORG. the heavens

-Dreyer, Tycho Brahe.

The observatory of Uraniborg the castle of at Hveen was an extraordinary establishment. In a large square inclosure oriented according to the points of the compass, were several observatories, a library, laboratory, living-rooms and, later, workshops, a paper-mill and printingpress, and even underground observatories. The whole establishment was administered with lavish extravagance, while Tycho was neither careful of his obligations nor free from arbitrary arrogance in his personal and administrative relations. In spite of these difficulties" a magnificent series of observations, far transcending in accuracy and extent anything that had been accomplished by his predecessors" was carried on for not less than 21 years. At the same time medicine and alchemy were also cultivated.

Concerned as he was to secure the greatest possible accuracy, Tycho constructed instruments of great size; for example, a wooden quadrant for outdoor use with a brass scale of some ten feet radius, permitting readings to fractions of a minute.

The best artists in Augsburg, clockmakers, jewellers, smiths, and carpenters, were engaged to execute the work, and from the zeal which so noble an instrument inspired, the quadrant was completed in less than a month. Its size was so great that twenty men could with difficulty transport it to its place of fixture. The two principal rectangular radii were beams of oak; the arch which lay between their extremities was made of solid wood of a particular kind, and the whole was bound together by twelve beams. It received additional strength from several iron bands, and the arch was covered with plates of brass, for the purpose of receiving the 5400 divisions into which it was to be subdivided. A large and strong pillar of oak, shod with iron, was driven into the ground, and kept in its place by solid

mason work. To this pillar the quadrant was fixed in a vertical plane, and steps were prepared to elevate the observer, when stars of a low altitude required his attention. As the instrument could not be conveniently covered with a roof, it was protected from the weather by a covering made of skins; but notwithstanding this and other precautions, it was broken to pieces by a violent storm, after having remained uninjured for the space of five years. - Brewster.

A smaller but more serviceable azimuth quadrant of brass gave angles to the nearest minute. He had a copper globe constructed at great expense with the positions of some 1000 stars carefully marked upon it.

The very precision of his observations tended to confirm his scepticism of the Copernican hypothesis, as it seemed incredible that the earth's supposed orbital motion should cause no change which he could detect in the position and brightness of the stars. He was also misled by supposing that the stars had measurable angular magnitude. He was not successful in making any fundamental improvement in the relatively crude methods of time measurement, depending himself on wheel-mechanism without the regulating pendulum, and an apparatus of the sand-glass or clepsydra type.

In 1577 Tycho made observations on a brilliant comet, and drew from them important theoretical inferences; namely, that instead of being an atmospheric phenomenon, the comet was at least three times as remote as the moon, and that it was revolving about the sun at a greater distance than Venus - unimpeded by the familiar crystalline spheres. He was even led, in discussing apparent irregularities of its motion, to suggest that its orbit might be oval-foreshadowing one of Kepler's great discoveries. According to the current view of his time, comets

were formed by the ascending from the earth of human sins and wickedness, formed into a kind of gas, and ignited by the anger of God. This poisonous stuff falls down again on people's heads, and causes all kinds of mischief, such as pestilence, Frenchmen (!), sudden death, bad weather, etc. - Dreyer, Tycho Brahe.