901 



BRAKE, TYCHO. 



BRAKE, TYCHO. 



eoz 



and of their proximate cause by Newton. There are many instances 

 iu which good fortune seems to have made a result of more importance 

 than the discoverer had any right to presume, either from the skill or 

 labour employed in obtaining it ; but iu the case of Tycho Brahd we 

 believe we are joined by a very large majority in thinking that fortune 

 deputed her office, pro hue vice, to justice, and that the eminence of 

 the success to which he has led the way is no more than is due to the 

 excellence of the means which he employed, and the sagacity he dis- 

 played in combining his materials. Where Hipparchus and Ptolemy 

 have left half a degree of uncertainty, Tycho Brah^ left two minutes, 

 if not one only. This Bradley afterwards reduced to as many seconds, 

 in the case of the stars ; and the ages of these three are the great 

 epochs of astronomy, as a science of pure observation. 



quarter of a minute of space, or less, to as much as two minutes. The 

 telescope was not then invented which shows that this is an optical 

 delusion, and that they are points of immeasurably small diameter. It 

 was certain to Tycho Brails' that if the earth did move, the whole 

 motion of the earth in its orbit did not alter the place of the stars by 

 two minutes ; and that consequently they must be so distant, that to 

 have two minutes of apparent diameter, they must be spheres of as 

 great a radius at least as the distance from the sun to the earth. This 

 latter distance Tycho Brand supposed to be 1150 times the semi- 

 diameter of the earth, and the sun about 180 times as great as the 

 earth. Both suppositions are grossly incorrect ; but they were common 

 ground, being nearly those of Ptolemy and Copernicus. It followed 

 then, for anything a real Copeniican could show to the contrary, that 



We must now devote some space to the system which he promul- 

 gated against that of Copernicus, and which is considered as the great 

 defect in his astronomy. And first, we must observe that it has been 

 customary to keep the name of Copernicus under every improvement 

 which his system has undergone in later times. His notions were 

 received at his hands loaded with real difficulties, supported by 

 arguments as trivial as those of his opponents ; Galileo has answered 

 the mechanical objections, Bradley has produced positive proofs, 

 Newton bus so altered the system that Copernicus would neither know 

 it nor admit it, by overthrowing the idea that the sun was fixed in the 

 centre of the universe (which is the real Copernican system) ; and thus 

 mended in one part, augmented in another, overthrown in a third, 

 and positively proved in a fourth, all that is known of the relative 

 motions of the system in modern times is removed back two hundred 

 years, called Copernican, and confronted with Tyeho Brand. Now 

 the real state of the case is this : that Tycho Brand did compound out 

 of the systems of Ptolemy and Copernicus a system of his own, which, 

 while it seized by fr the greater portion of the advantages of the 

 latter, was not open to the most material objection. (See a paper 

 entitled ' Old Arguments against the Motion of the Earth,' ' Companion 

 to the Almanac,' 1836.) And we assert moreover, that of all the incon- 

 clusive arguments of that day, which concern the subject in question, 

 the reply of the Copernicans to Tycho Brand is the most inconclusive. 

 The system of Tycho Brand consists in supposing, 1, that the stars all 

 move round the earth as in the Ptolemaic system ; 2, that all the 

 planets, except the earth, move round the sun as in the Copernican 

 system ; 3, that the sun, and the imaginary orbits in which the planets 

 are moving, are carried round the earth. Imagine a planetarium on 

 the system of Copernicus placed over a table, above which is a light. 

 As the earth moves, let the whole machine be always so moved that 

 the shadow of the earth shall fall upon one and the same part of the 

 table ; then the motions of the shadows of the other planets and of 

 the sun will be according to the system of Tycho Brand. Mathemati- 

 cally speaking, it does not differ from that of Copernicus : we shall 

 now consider it physically. 



The stars, to the naked eye, present diameters varying from a 



some of the fixed stars must be 1520 millions of times as great as the 

 earth, or 9 millions of times as great as they supposed the suu to bo 

 Now, one of the strong arguments against Ptolemy (and the one which 

 has generally found its way into modern works) was the enormous 

 motion which he supposed the stars to have. The Copernican of that 

 day might have been compelled to choose between an incomprehen- 

 sibly great magnitude and a similar motion. Delambre, who comments 

 with brief contempt upon the several arguments of Tycho Brahe', has 

 here only to say, " We should now answer that no star has an apparent 

 diameter of a second." Undoubtedly, but what would you have 

 answered then, is the reply. The stars were spheres of visible magni- 

 tude, and are so still ; nobody can deny it who looks at the heavens 

 without a telescope : did Tycho reason wrong because he did not know 

 a fact which could only be known by an instrument invented after 

 his death ? 



Again, the mechanical difficulties attending the earth's motion were 

 without any answer which deserved attention even in that day. That 

 a stone dropped from a height fell directly under the point it was 

 dropped from, Copernicus accounts for by supposing that the air 

 carries it : he, as well as his opponents, believing that but for the air 

 the spot at first directly beneath the stone would move from under 

 it. We are of opinion that the system of Tycho Brah<5 W.TS the only 

 one of that day not open to serious physical objections, taking as a 

 basis the notions of mechanics admitted by all parties. To us the 

 system of Copernicus appears a premature birth : the infant long 

 remained sickly, and would certainly have died if it had not fallen 

 under better management than that of its own parents. 



Frederick II. died in 1588, and Tycho remained unmolested under 

 his son Christian IV. till 1596. Gassendi relates that the nobles were 

 envious when they saw foreigners of importance come to Denmark 

 solely to converse with Tycho ; that the medical men were displeased 

 at his dispensing medicines gratis to the poor ; and that the minister 

 had a quarrel with Tyeho about a dog. Malte-Brun relates this more 

 distinctly, apparently from the ' Danske Magazin,' or from Holberg's 

 ' History of Denmark ;' so that it seetns most probable that the 

 destruction of the observatory at Hoe'ne arose from a personal 



